Final environmental impact statement double-crested cormorant management in the United States

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U.S. Fish and Wildlife Service
Final Environmental Impact Statement
Double-crested Cormorant Management in the United
States
U.S. Department of Interior Fish and Wildlife Service
“Working with others to conserve, protect, and enhance fish, wildlife, and
plants and their habitats for the continuing benefit of the American people”
in cooperation with
U.S. Department of Agriculture APHIS Wildlife Services
“Providing leadership in wildlife damage management in the protection of
America’s agricultural, industrial and natural resources, and safeguarding public
health and safety”
2003
i
FINAL ENVIRONMENTAL IMPACT STATEMENT:
Double-crested Cormorant Management
RESPONSIBLE AGENCY: Department of the Interior
U.S. Fish and Wildlife Service
COOPERATING AGENCY: Department of Agriculture
Animal and Plant Health Inspection Service
Wildlife Services
RESPONSIBLE OFFICIAL: Steve Williams, Director
U.S. Fish and Wildlife Service
Main Interior Building
1849 C Street
Washington, D.C. 20240
FOR FURTHER INFORMATION
CONTACT: Shauna Hanisch, EIS Project Manager
Division of Migratory Bird Management
U.S. Fish and Wildlife Service
4401 N. Fairfax Drive MS-MBSP-4107
Arlington, Virginia 22203
(703) 358-1714
Brian Millsap, Chief
Division of Migratory Bird Management
U.S. Fish and Wildlife Service
4401 N. Fairfax Drive MS-MBSP-4107
Arlington, Virginia 22203
(703) 358-1714
ii
SUMMARY
Populations of Double-crested Cormorants have been increasing rapidly in many parts of
the U.S. since the mid-1970s. This abundance has led to increased conflicts, both real
and perceived, with various biological and socioeconomic resources, including
recreational fisheries, other birds, vegetation, and hatchery and commercial aquaculture
production. This document describes and evaluates six alternatives (including the
proposed action) for the purposes of reducing conflicts associated with cormorants,
enhancing the flexibility of natural resource agencies to deal with cormorant conflicts,
and ensuring the long-term conservation of cormorant populations. There are four
chapters that make up the critical components of an Environmental Impact Statement.
Chapter 1, Purpose and Need, describes the purpose of and need for the action. Chapter
2, Alternatives, describes the six management alternatives that we considered: (1)
Continue current cormorant management practices (No Action); (2) implement only non-lethal
management techniques; (3) expand current cormorant damage management
practices; (4) establish a new depredation order to address public resource conflicts
(PROPOSED ACTION); (5) reduce regional cormorant populations; and (6) establish
frameworks for a cormorant hunting season. Chapter 3, Affected Environment, introduces
the reader to the environmental categories upon which the analysis of alternatives in
chapter 4 is based: cormorant populations, fish, other birds, vegetation, Federally-listed
Threatened and Endangered species, water quality and human health, economic impacts,
fish hatcheries and environmental justice, property losses, and existence and aesthetic
values. Chapter 4, Environmental Consequences, analyzes the predicted impacts of each
alternative on the environmental categories outlined in chapter 3 and in comparison to the
No Action alternative. The environmental analysis presented in Chapter 4 indicates that
the PROPOSED ACTION: will cause the estimated take of <160,000 DCCOs, which is
not predicted to have a significant negative impact on regional or continental DCCO
populations; will cause localized disturbances to other birds but these can be minimized
by taking preventive measures, leading to the action having beneficial effects overall;
will help reduce localized fishery and vegetation impacts; will not adversely affect any
Federally-listed species; is likely to help reduce localized water quality impacts; will help
reduce depredation of aquaculture and hatchery stock; is not likely to significantly benefit
recreational fishing economies or commercial fishing; may indirectly reduce property
damages; and will have variable effects on existence and aesthetic values, depending on
perspective.
iii
TABLE OF CONTENTS
CHAPTER 1: PURPOSE OF AND NEED FOR ACTION.............................................................1
1.1 Introduction...................................................................................................................1
1.2 Purpose of Action..........................................................................................................2
1.3 Need for Action.............................................................................................................2
1.3.1 Biological...................................................................................................2
1.3.2 Socioeconomic...........................................................................................3
1.4 Background Information...............................................................................................3
1.4.1 Lead and Cooperating Agencies................................................................3
1.4.2 Policy, Authority, and Legal Compliance.................................................3
1.4.3 Other Considerations.................................................................................6
1.4.4 Cormorant Management Practices............................................................8
1.4.5 The Role of Other Agencies in Cormorant Management.......................11
CHAPTER 2: ALTERNATIVES...................................................................................................13
2.1 Introduction..................................................................................................................13
2.2 Rationale for Alternative Design.................................................................................13
2.3 Proposed Action...........................................................................................................13
2.4 Description of Alternatives..........................................................................................13
2.4.1 Alternative A: No Action.............................................................................13
2.4.2 Alternative B: Non-lethal Management.......................................................15
2.4.3 Alternative C: Increased Local Damage Control.........................................16
2.4.4 Alternative D: Public Resource Depredation Order (PROPOSED ACTION)
..............................................................................................................................17
2.4.5 Alternative E: Regional Population Reduction...........................................18
2.4.6 Alternative F: Regulated Hunting...............................................................19
2.5 Alternatives Considered but Eliminated from Detailed Study....................................19
2.5.1 No Management..........................................................................................19
2.5.2 Rescindment of MBTA Protection..............................................................19
2.6 Comparison of Alternatives.........................................................................................19
CHAPTER 3: AFFECTED ENVIRONMENT...............................................................................22
3.1 Introduction..................................................................................................................22
3.2 Biological Environment...............................................................................................22
3.2.1 Double-crested Cormorants.........................................................................22
3.2.2 Fish...............................................................................................................31
3.2.3 Other Birds...................................................................................................35
3.2.4 Vegetation....................................................................................................38
3.2.5 Federally-listed Species...............................................................................38
3.3 Socioeconomic Environment.......................................................................................39
3.3.1 Water Quality and Human Health...............................................................39
3.3.2 Economic Environment...............................................................................40
3.3.3 Fish Hatcheries and Environmental Justice................................................45
3.3.4 Property Losses...........................................................................................46
3.3.5 Existence and Aesthetic Values..................................................................46
3.3.6 Issues Raised but Eliminated from Detailed Study....................................47
CHAPTER 4: ENVIRONMENTAL CONSEQUENCES.............................................................51
4.1 Introduction.................................................................................................................51
iv
4.2 Environmental Analysis of Alternatives....................................................................52
4.2.1 Impacts to Double-crested Cormorants.......................................................52
4.2.2 Impacts to Fish............................................................................................59
4.2.3 Impacts to Other Birds................................................................................66
4.2.4 Impacts to Vegetation.................................................................................75
4.2.5 Impacts to Federally-listed Species...........................................................78
4.2.6 Impacts to Water Quality and Human Health............................................80
4.2.7 Economic Environment..............................................................................82
4.2.8 Impacts to Hatcheries and Environmental Justice......................................92
4.2.9 Impacts to Property Losses..........................................................................95
4.2.10 Impacts to Existence and Aesthetic Values..............................................96
4.3 Further Discussion of Alternatives..............................................................................98
4.3.1 Alternative A: No Action............................................................................98
4.3.2 Alternative B: Non-lethal Management....................................................100
4.3.3 Alternative C: Increased Local Damage Control......................................101
4.3.4 Alternative D: Public Resource Depredation Order (PROPOSED ACTION)
............................................................................................................................103
4.3.5 Alternative E: Regional Population Reduction.........................................105
4.3.6 Alternative F: Regulated Hunting.............................................................106
4.3.7 Mitigating Measures.................................................................................107
CHAPTER 5: LIST OF PREPARERS.........................................................................................114
CHAPTER 6: CONSULTATION AND COORDINATION AGENCIES..................................116
6.1 Introduction...............................................................................................................116
6.2 Issues of Concern and Management Options Identified During Scoping................116
6.3 Public Comments Expressed During the DEIS Comment Period............................117
6.4 List of Agencies, Organizations, and Individuals.....................................................119
CHAPTER 7: PUBLIC COMMENT ON DEIS AND RESPONSE...........................................121
CHAPTER 8: REFERENCES CITED........................................................................................139
APPENDICES
Appendix 1: List of Scientific Names
Appendix 2: Distribution of DCCO Breeding Colonies in North America
Appendix 3: DCCO Foraging Behavior at Aquaculture Facilities
Appendix 4: DCCO Management Techniques
Appendix 5: Methodology for Estimating Take under the Aquaculture Depredation Order
Appendix 6: Discussion of Fishery Impacts
Appendix 7: Guidelines for Distinguishing DCCOs from Anhingas and Neotropic Cormorants
Appendix 8: Overview of Aquaculture Production in 13 States
Appendix 9: Costs of Control Methods and Techniques
Appendix 10: Comparison Tables Using Christmas Bird Count Data
Appendix 11: Public Scoping Report
1 – Chapter 1
CHAPTER 1: PURPOSE OF AND NEED FOR ACTION
1.1 Introduction
The persistence of conflicts associated with Double-crested Cormorants (hereafter,
DCCOs or cormorants; see Appendix 1 for a list of scientific names), widespread public
and agency dissatisfaction with the status quo, and the desire to develop a more
consistent and effective management strategy for DCCOs led the U.S. Fish & Wildlife
Service (Service or we) to reexamine, and if deemed necessary, to amend our policies and
practices for the management of cormorants in the contiguous United States.
We chose to prepare an Environmental Impact Statement (EIS), as suggested by National
Environmental Policy Act (NEPA) guidelines, including: (1) Council on Environmental
Quality (CEQ) regulations in 40 CFR 1508.18, which define a “major Federal action” as
“adoption of formal plans, such as official documents prepared or approved by Federal
agencies which guide or prescribe alternative uses of Federal resources, upon which
future agency actions will be based;” and (2) Service policy in section 550FW 3.3B(2)
which states that criteria triggering the preparation of an EIS include precedent-setting
actions with wide-reaching or long-term implications, changes in Service policy having a
major positive or negative environmental effect, and/or conflicts with local, regional,
State or Federal proposed or adopted plans or policies.
As stated in 40 CFR 1502.1, the purpose of an EIS is to provide a detailed explanation of
the significant environmental consequences, both good and bad, of a proposed action.
This explanation includes significant effects on the natural, economic, social, and cultural
resources of the affected environment. An EIS is to be prepared to inform decision-makers
and the public of the proposed action and its reasonable alternatives. It should
focus on significant environmental issues. This Final EIS (FEIS) identifies and provides
an evaluation of six alternative approaches for managing DCCOs, including the proposed
action (Alternative D). Each alternative is analyzed based on anticipated impacts to
various biological and socioeconomic impact areas. This FEIS is a comprehensive,
programmatic plan intended to guide and direct DCCO management activities in the 48
States (excluding Hawaii and Alaska). Where NEPA analysis is suggested or required
for site-specific control projects carried out under the guidance of this document,
analyses would “tier to” or reference the FEIS. Site-specific NEPA analysis would focus
on issues, alternatives, and environmental effects unique to the project.
Because of the important role of the Wildlife Services program of the USDA Animal and
Plant Health Inspection Service (APHIS/WS) in DCCO management and research, and
the need for interagency coordination in developing future cormorant management
strategies, this FEIS is being prepared cooperatively by the Service and APHIS/WS.
This section of the FEIS discusses the purpose of and need for the action, gives
background information on the lead and cooperating agencies and the legal and policy
context of the action, describes current DCCO management activities, and summarizes
public involvement in this issue.
2 – Chapter 1
1.2 Purpose of Action
In recent years, increasing populations of DCCOs have led to growing concern from the
public and natural resource management professionals about impacts of DCCOs on
various human and natural resources. Based on internal and interagency scoping and the
direction set forth in 40 CFR 1508.18 and 550 FFW3.3B (described in further detail
below), we published a Notice of Intent in the Federal Register on November 8, 1999 (64
FR 60826) announcing that we would prepare, in cooperation with APHIS/WS, an EIS
and national management plan “to [address] impacts caused by population and range
expansion of the double-crested cormorant in the contiguous United States.”
The purpose of the proposed action is threefold: to reduce resource conflicts associated
with DCCOs in the contiguous United States, to enhance the flexibility of natural
resource agencies in dealing with DCCO-related resource conflicts, and to ensure the
long-term conservation of DCCO populations.
1.3 Need for Action
While cormorant-human conflicts are not new, from either a historical or a global
perspective (Siegel-Causey 1999; Hatch 1995, van Eerden et al. 1995, Wires et al. 2001),
the DCCO’s rapid population increase over the past 25 years has brought these conflicts
in the U.S. to the point of justifying greater management attention. There is a need for
the Service to allow others to conduct DCCO control to limit negative impacts to the
maximum extent practicable.
The issue of “need” can also be considered from the perspective of other agencies and
parties with a stake in DCCO management. APHIS/WS issued a position statement
emphasizing the need for scientifically-based DCCO population reduction in order to
reduce impacts to aquaculture producers and other resources. Of the 27 States that
commented during the public scoping period, 16 of these expressed desire for increased
management flexibility and/or greater population management of DCCOs. Many non-agency
stakeholders also stated that there is a need for increased DCCO control to reduce
resource impacts.
1.3.1 Biological
The recent increase in the North American DCCO population, and subsequent range
expansion, has been well-documented (Scharf and Shugart 1981, Milton and Austin-
Smith 1983, Buckley and Buckley 1984, Hatch 1984, Ludwig 1984, Blokpoel and
Harfenist 1986, Price and Weseloh 1986, Roney 1986, Craven and Lev 1987, Hobson et
al. 1989, Hatch 1995, Weseloh et al. 1995, Glahn et al. 1999, Tyson et al. 1999, Hatch
and Weseloh 1999, Wires et al. 2001). There is a need to reduce the biological impacts
resulting from this population increase which include: adverse effects on other bird
species through habitat destruction, exclusion, and/or nest competition; declines in fish
populations associated with DCCO predation; destruction of vegetation, particularly
where DCCOs nest; and predation on Federally-listed fish species. There is a need to
provide for localized variation in DCCO control because the occurrence and severity of
these impacts varies from region to region.
3 – Chapter 1
1.3.2 Socioeconomic
Socioeconomic impacts include economic losses to aquaculture producers, commercial
fisheries, and fishing-related businesses; losses to private resources (including fish in
private lakes and damaged trees); and compromised water quality. As with biological
impacts, the occurrence and severity of these impacts varies from region to region. There
is a need to reduce these impacts.
1.4 Background Information
1.4.1 Lead and Cooperating Agencies
USDI Fish and Wildlife Service. The primary responsibility of the Service is fish,
wildlife, and plant conservation. Our mission is “working with others to conserve,
protect, and enhance fish, wildlife, and plants and their habitats for the continuing benefit
of the American people.” While some of the Service's responsibilities are shared with
other Federal, State, Tribal, and local entities, we have special authorities in managing
the National Wildlife Refuge System; conserving migratory birds, endangered species,
certain marine mammals, and nationally significant fisheries; and enforcing Federal
wildlife laws. The Division of Migratory Bird Management mission is “providing global
leadership in the conservation and management of migratory birds for present and future
generations.” One of the Service’s long-term goals, as stated in the 2000-2005 Service
Strategic Plan, is “migratory bird conservation.” The purpose of this goal is “to improve
the status of migratory bird populations that have evidenced decline or other significant
problems, including overabundance.”
USDA Animal and Plant Health Inspection Service-Wildlife Services. The Wildlife
Services program of the U.S. Department of Agriculture Animal and Plant Health
Inspection Service (APHIS/WS) is responsible for managing conflicts with and damages
caused by wildlife, including migratory birds. APHIS/WS' mission is to “provide
leadership in wildlife damage management in the protection of America's agricultural,
industrial and natural resources, and to safeguard public health and safety.” This is
accomplished through: training of wildlife damage management professionals;
development and improvement of strategies to reduce economic losses and threats to
humans from wildlife; collection, evaluation, and dissemination of management
information; cooperative wildlife damage management programs; informing and
educating the public on how to reduce wildlife damage and; providing data and a source
for limited use management materials and equipment, including pesticides (USDA-APHIS
1989).
1.4.2 Policy, Authority, and Legal Compliance
Migratory Bird Treaty Act of 1918, as amended (16 U.S.C. 703-711: 40 Stat. 755).
The Service has the primary statutory authority to manage migratory bird populations in
the United States, authority which comes from the Migratory Bird Treaty Act (MBTA).
The original treaty was signed by the U.S. and Great Britain (on behalf of Canada) in
1918 and imposed certain obligations on the U.S. for the conservation of migratory birds,
including the responsibilities to: conserve and manage migratory birds internationally;
sustain healthy migratory bird populations for consumptive and non-consumptive uses;
and restore depleted populations of migratory birds. Conventions with Mexico, Japan,
4 – Chapter 1
and Russia occurred in later years. The cormorant taxonomic family, Phalacrocoracidae,
and 31 other families were added to the List of Migratory Birds (that is, those bird
species protected by the MBTA) in 1972 as a result of an amendment to the 1936
“Convention between the United States of America and the United Mexican States for the
Protection of Migratory Birds and Game Mammals” (23 U.S.T. 260, T.I.A.S. 7302).
Thus, since 1972, DCCOs have been a trust resource managed by the Service for the
American people under the authority of the MBTA.
Animal Damage Control Act of 1931 and Rural Development, Agriculture, and Related
Agencies Appropriations Act of 1988 (7 U.S.C. 426-426c; 46 Stat. 1468).
The U.S. Department of Agriculture is directed by law to protect American agriculture
and other resources from damage associated with wildlife. The primary statutory
authority for the APHIS/WS program is the Animal Damage Control Act of March 2,
1931 (7 U.S.C. 426-426c; 46 Stat. 1468), as amended in the Fiscal Year 2001 Agriculture
Appropriations Bill, which provides that:
The Secretary of Agriculture may conduct a program of wildlife services with respect to injurious animal
species and take any action the Secretary considers necessary in conducting the program. The Secretary
shall administer the program in a manner consistent with all of the wildlife services authorities in effect on
the day before the date of the enactment of the Agriculture, Rural Development, Food and Drug
Administration, and Related Agencies Appropriations Act, 2001.
Since 1931, with the changes in societal values, APHIS/WS policies and programs place
greater emphasis on the part of the Act discussing “bringing [damage] under control,”
rather than “eradication” and “suppression” of wildlife populations. In 1988, Congress
strengthened the legislative mandate of APHIS/WS with the Rural Development,
Agriculture, and Related Agencies Appropriations Act. This Act states, in part:
That hereafter, the Secretary of Agriculture is authorized, except for urban rodent control, to conduct
activities and to enter into agreements with States, local jurisdictions, individuals, and public and private
agencies, organizations, and institutions in the control of nuisance mammals and birds and those mammal
and bird species that are reservoirs for zoonotic diseases, and to deposit any money collected under any
such agreement into the appropriation accounts that incur the costs to be available immediately and to
remain available until expended for Animal Damage Control activities.
Endangered Species Act (ESA), as amended (7 U.S.C. 136; 16 U.S.C. 460 et seq.).
It is Federal policy, under the ESA, that all Federal agencies seek to conserve threatened
and endangered species and utilize their authorities in furtherance of the purposes of the
Act (Sec.2(c)). In accordance with section 7 of the Act, the Service has prepared a
Biological Evaluation and conducted informal consultation with the Service Endangered
Species Program to evaluate Federally-listed species that may be affected by the
proposed action.
National Environmental Policy Act of 1969 (NEPA), as amended (42 U.S.C. 4321-4347).
NEPA is our national charter for protection of the environment; it requires Federal
agencies to evaluate the potential environmental impacts when planning a major Federal
action and ensures that environmental information is available to public officials and
citizens before decisions are made and before actions are taken.
5 – Chapter 1
In general, the NEPA process entails: determining what need must be addressed;
identifying alternative ways of meeting the need; analyzing the environmental impacts of
each alternative; and deciding which alternative to pursue and how. While NEPA does
not place environmental protection over all other public values, it does require a thorough
consideration of the environmental impacts associated with management actions. NEPA
neither requires a particular outcome nor that the “environmentally-best” alternative is
selected. It mandates a process for thoroughly considering what an action may do to the
human environment and how any adverse impacts can be mitigated
(http://npi.org/nepa/process.html).
More specifically, there are seven major steps in the planning process for the
development of an EIS and the implementation of the proposed action. These include:
1) Publication of Notice of Intent – The Notice of Intent to prepare an Environmental
Impact Statement and national cormorant management plan was published in the Federal
Register (64 FR 60826) on November 8, 1999. This initiated the scoping process.
2) Identification of Issues and Concerns – The Notice of Intent solicited public
participation in the scoping process, which is the chief way that issues, concerns, and
potential management options are communicated from the public to the lead agency. In
addition to writing or e-mailing comments, citizens could attend any of twelve public
meetings held across the country. The scoping period ended on June 30, 2000. All
comments were read, compiled, and summarized in a public scoping report.
3) Development of Alternatives – Following scoping, six alternatives were developed to
offer a range of options for managing DCCOs. These were based on NEPA regulations,
public comments, interagency meetings, internal discussion, and review of available
scientific information.
4) Analysis of Environmental Effects – After significant issues and alternatives were
established, the environmental analysis was prepared in order to help the public and
decision-makers understand the environmental consequences of the various alternatives.
5) Publication of Notice of Availability of Draft Environmental Impact Statement – The
notice of availability for the DEIS was published in the Federal Register on December 3,
2001 (66 FR 60218) and announced the completion of the DEIS and its availability for
public review. It was followed by 10 public meetings and a 100-day comment period.
6) Publication of Notice of Availability of Final Environmental Impact Statement – This
Federal Register publication follows the public comment period for the DEIS and
announces the completion of the Final EIS, followed by a 30-day waiting period.
7) Publication of Record of Decision – This is the final step of the EIS decision-making
process, which states the selected alternative and why it was chosen. The actions
associated with the EIS cannot be taken until the Record of Decision is issued.
6 – Chapter 1
Environmental Justice and Executive Order 12898. Executive Order 12898, entitled
“Federal Actions to Address Environmental Justice in Minority Populations and Low-
Income Populations,” promotes the fair treatment of people of all races, income levels
and cultures with respect to the development, implementation and enforcement of
environmental laws, regulations and policies. Environmental justice is the pursuit of
equal justice and protection under the law for all environmental statutes and regulations
without discrimination based on race, ethnicity, or socioeconomic status.
Executive Order 13186. Executive Order 13186, entitled “Responsibilities of Federal
Agencies to Protect Migratory Birds,” directs any Federal agency whose actions have a
measurable negative impact on migratory bird populations to develop a Memorandum of
Understanding (MOU) with the Service to promote conservation of migratory birds. The
MOUs would identify positive actions that Federal agencies can apply to ensure their
activities consider the conservation of migratory birds. The Executive Order (EO) also
requires the Secretary of Interior to establish a Council for the Conservation of Migratory
Birds to oversee implementation of the EO. The council will be composed of
representatives from the Departments of Interior, Commerce, Agriculture, State,
Transportation, Energy, and Defense; the Environmental Protection Agency; and other
agencies as appropriate.
1.4.3 Other Considerations
Conceptual Foundations. “Conceptual foundations” are the set of principles and
assumptions that direct management activities (Anderson 1991). They influence how we
interpret information, identify problems, and select approaches to their resolution (ISG
1999). Similarly, they are an expression of agency goals and philosophy, which guide
management decisions. The following five statements form the conceptual foundations
on which DCCO management is based:
(1) DCCOs are an international migratory bird resource and as such they have inherent
value regardless of their direct use to humans;
(2) While DCCOs have undergone recent range expansions, they are native to North
America;
(3) DCCOs are predators that, while a natural part of the ecosystem, can compete with
humans for fisheries, with consequences of varying ecological and socioeconomic
significance;
(4) DCCO populations have increased significantly in the past 25 years in North America
and this increase has led to both real and perceived resource conflicts;
(5) There are sound biological and socioeconomic rationales for developing a
comprehensive DCCO management strategy in the U.S.
Human Dimensions. Wildlife management is fundamentally a human, or social,
construct. One popular introductory wildlife ecology text noted that, “the practice of
wildlife management is rooted in the intermingling of human ethics, culture, [and]
perceptions” (Robinson and Bolen 1989). As human populations have grown and placed
greater demands on nature, and as human values toward wildlife resources have become
increasingly diverse, the need to better understand the “human dimensions” side of
7 – Chapter 1
wildlife management has increased. Human dimensions entail “identifying what people
think and do regarding wildlife, understanding why, and incorporating that insight into
policy and management decision-making processes and programs” (Decker and
Lipscomb 1991). Thus, human dimensions address the social nature of today’s natural
resource problems (Manfredo et al. 1998), with particular relevance to “people-wildlife
problems” in which the behavior of wildlife creates a negative impact for some
stakeholders, or is perceived by some stakeholders as having adverse impacts (Decker
and Chase 1997). In a paper discussing the “social causes of the cormorant revival in the
Netherlands” (where Great Cormorants have become an overabundant species) the
authors (van Bommel et al. 2003) stated:
Ecological processes determine the potential cormorant population but social processes play a large role in
determining the actual cormorant population. Ecological systems function within the subjective boundaries
set by [people]… A problem situation can occur in which different parties disagree on the definition of
these boundaries (Pretty 1995, Pimbert and Pretty 1995). This is often the case in nature conservation
because ecosystems carry a high level of intrinsic uncertainty… When dealing with these uncertainties,
people will have different views and opinions on reality.
At a 1998 workshop on cormorant management in New York, participants agreed that
human dimensions are important in the DCCO issue because: (1) economics and
recreation are important factors; (2) it is an emotional issue that can cause polarization;
and (3) it accentuates the conflict between politics and science-based management. For
these reasons and others, the DCCO conflict can be viewed as a classic “people-wildlife
problem,” entailing both biological and social elements. The social element is made
prominent by the fact that, just as with other examples of abundant species management,
from white-tailed deer to Canada Geese, public perception of the proper way to deal with
the problem varies considerably. Conover (2002) wrote that the government’s role in
wildlife management is “to regulate the harvest of wildlife by people, to restrict human
behavior that would be detrimental to the wildlife resource, to conduct largescale
management activities, and to manage wildlife for the benefit of society.” Naturally, the
difficulty in doing so is because society is made up of diverse individuals who vary in
their perceptions of wildlife and how they want that resource managed. When conflicts
occur between wildlife and other resources that humans value, wildlife damage
management decisions must be made; these are difficult decisions to make because
stakeholder opinions are often highly polarized.
In regard to societal expectations in natural resource controversies, the Great Lakes
Fishery Resources Restoration Study (USFWS 1995), in a discussion on decision-making
and public expectations, stated:
When different segments of society place competing demands on nature, conflicts are inevitable and often
contentious... Agencies and publics are often prevented from realizing resource potential when special
interest groups fail to recognize public trust responsibilities…and the legitimacy and roles of other users.
The director of the Montana Department of Fish, Wildlife, and Parks, in the July/August
2002 edition of Montana Outdoors, succinctly described the unique position of public
agencies when he wrote:
8 – Chapter 1
Some have accused us of [being extreme], of being far too biased on one issue or another. Usually the
charge comes from those who disagree with our position… The fact is, we’re rarely on the extreme ends of
any issue. Nor should we be. We’re a public agency representing the diverse interests of all [Americans].
Not just the ones who yell the loudest. Not just the ones with the most money and political clout. And not
just the ones who buy licenses. What that means is that we often take a moderate position on issues. If it
appears that we ever go “too far” on any issue or policy, believe me when I say that I could always find a
group of citizens angry that we didn’t go nearly far enough… No matter how hard we try, we won’t be able
to make everyone happy. There will always be committed, well-meaning people on either side of an issue
who think we either sold out and didn’t do enough—or that we went way too far.
In sum, management of abundant wildlife populations is a particularly challenging aspect
of wildlife conservation, one that demands that decision-makers consider a number of
important biological and socioeconomic factors. As a public agency, the Service
recognizes the importance of social, political, and economic factors in policy-making, but
emphasizes that the foundation of the Service’s mission is fish and wildlife biology.
Thus we are committed to pursuing biologically justified management strategies that are
based on the best available science and, additionally, on the knowledge and experience of
wildlife resource professionals. It is here where Romesburg’s (1981) advice that “science
and planning are different kinds of decision-making” is most relevant. Planning is the
domain of wildlife management and it:
exposes alternative images of a future possible world to the decision-maker’s values, or preferences, and
selects the best image…the images in planning are composed of scientific knowledge, common sense, rule-of-
thumb knowledge, and theories that are as yet untested… Although science and planning share common
tools, science and planning have different norms for certifying ideas, and hence criticism of these tools
must take into account the domain of their use.
The Service and APHIS/WS recognize both the controversial nature of DCCO
management and the range of values reflected in public and professional views about best
management actions. This FEIS reflects full consideration of the diverse views brought
forth during public scoping and the DEIS comment period and provides an analytical
foundation on which to base final management decisions.
1.4.4 Cormorant Management Practices
Depredation Permits. While the MBTA provides migratory birds with protection from
unauthorized take, it maintains a high degree of flexibility for dealing with human-bird
conflicts (Trapp et al. 1995). According to the MBTA, the “take” of DCCOs is strictly
prohibited except as allowed under the terms of a migratory bird permit or pursuant to
regulations.
Depredation permits to take DCCOs have been issued by the Service since 1986 and may
allow the take of eggs, adults and young, or active nests. Guidelines governing permit
issuance for migratory birds are authorized by the MBTA and subsequent regulations (50
CFR Parts 13 and 21). Specifically, Part 21.41 of Subpart D of these regulations outlines
procedures for issuing permits for the control of depredating birds. These regulations
state that all private individuals, organizations, and Federal and State agencies seeking to
control migratory birds must file an application for a depredation permit that contains the
following information: (1) a description of the area where depredations are occurring; (2)
the nature of the crops or other interests being injured; (3) the extent of such injury; and
9 – Chapter 1
(4) the particular species of migratory birds committing the injury. Thus, Part 21.41
authorizes the take of migratory birds that are injuring “crops or other interests.” In
issuing depredation permits, the Service has historically interpreted “other interests” to
mean threatened and endangered species, property damage on private or public land, and
human health and safety, although permits have been issued to protect natural resources.
In 1990, Director’s Order No. 27 was instated which clarifies that the Service can issue
depredation permits for migratory, fish-eating birds preying on fish aquaculture and
hatchery facilities.
APHIS/WS typically responds to requests for assistance with bird depredation and
damage by collecting information on the type of resource being damaged, where the
damage is occurring, the number and species of birds responsible for the damage, the
economic losses resulting from the damage, and the control methods which have been
used in attempting to resolve the damage. Based upon these evaluations, APHIS/WS
personnel recommend an Integrated Damage Management approach for resolving bird
depredation and damage conflicts, which could include providing recommendations to
the Service for issuance of a depredation permit. While APHIS/WS provides
recommendations to the Service for the issuance of migratory bird depredation permits to
private entities in the cases of severe bird depredation and damage (Mastrangelo et al.
1997), the responsibility of issuing these permits rests solely with the Service (Trapp et
al. 1995). In most States, a permit is also needed from the State fish and wildlife agency.
APHIS/WS maintains a Management Information System (MIS) database documenting
the assistance that the agency provides in resolving wildlife damage conflicts. A review
of MIS data collected from FY 1995-2001 revealed that the agency responded to 1,916
technical assistance requests (“the provision of advice, recommendations, information, or
materials for use in managing wildlife damage problems” [USDA-APHIS 1997b]) to
reduce DCCO conflicts in 42 States, with Alabama, Arkansas, Florida, Louisiana,
Mississippi, and Texas representing 65 percent of the requests over the 7-year period.
MIS resource categories included aquaculture (commercially propagated finfish and
shellfish) with 72 percent of technical assistance requests; natural resources (habitat,
wildlife, wild fisheries) with 19 percent of requests; property (structures, boats,
automobiles, aircraft, pets, timber/trees) with 6 percent of requests; and human health and
safety (disease transmission to humans, wildlife aircraft strikes, direct personal injury)
with 3 percent of requests. Of those 1,916 requests, APHIS/WS recommended the
issuance of 533 depredation permits to the Service, of which over 95 percent were for the
protection of aquaculture and natural resources.
Depredation Order. In 1998, the Service issued a depredation order (USFWS 1998b; 50
CFR 21.47 ) authorizing commercial freshwater aquaculture producers in 13 States
(Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Minnesota, Mississippi,
North Carolina, Oklahoma, South Carolina, Tennessee, and Texas) to take DCCOs,
without a Federal permit, when found committing or about to commit depredations to
aquaculture stocks. The depredation order states that DCCOs may be taken by shooting
only during daylight hours, and only when necessary to protect freshwater commercial
10 – Chapter 1
aquaculture and State-operated hatchery stocks and that such actions must be carried out
in conjunction with a non-lethal harassment program certified by APHIS/WS officials.
Research and Population Surveys. Prior to 1950, the U.S. Biological Survey (predecessor
of the Fish and Wildlife Service) conducted extensive food habits studies on DCCOs and
other fish-eating birds across the continent, with particular emphasis on potential
economic impacts. More recently, the Service has conducted or funded several site-specific
studies of cormorant food habits in areas such as the Penobscot River and upper
Penobscot Bay, Maine; Les Cheneaux Islands, Michigan; and the Mississippi River
Delta, Mississippi. In 1999, the Service provided funding for a DCCO population status
assessment to be prepared by researchers from the University of Minnesota and utilized
in the development of this EIS (Wires et al. 2001). This report, “The Status of the
Double-Crested Cormorant (Phalacrocorax auritus) in North America,” is available
online at http://migratorybirds.fws.gov/issues/cormorant/status.pdf.
DCCO population monitoring is carried out cooperatively by the Service, APHIS/WS,
the Canadian Wildlife Service, the States, and various universities. The U.S. Geological
Survey (Patuxent Wildlife Research Center) and non-governmental organizations
participate in recording and analyzing the population data. The various types of surveys
include the Great Lakes Colonial Waterbird Survey, Atlantic Coast Colonial Waterbird
Survey, winter roost surveys, Christmas Bird Counts, and Breeding Bird Surveys.
Additionally, the APHIS/WS National Wildlife Research Center is involved in a variety
of DCCO research projects, including controlled experiments to assess DCCO impacts to
gross catfish production; a two-year satellite telemetry study in Alabama, Arkansas,
Louisiana, and Mississippi aimed at monitoring migratory movements of DCCOs
captured at aquaculture areas; a two-year satellite telemetry study in eastern Lake Ontario
(in cooperation with the New York State Department of Environmental Conservation)
aimed at assessing the efficacy of control activities at the Little Galloo Island breeding
colony in eastern Lake Ontario; development of a deterministic population model for
DCCOs; and preparation of a report titled “A Science-Based Initiative to Manage
Double-Crested Cormorant Damage to Southern Aquaculture.”
Information and Education Outreach. The Service participates in outreach activities to
respond to public concerns and to educate the public about DCCOs. In 1998, the
Service’s Division of Migratory Bird Management developed a fact sheet on DCCOs,
and placed it on its website at http:// migratorybirds.fws.gov/issues/cormorant/
cormorant.html. Subsequently, the cormorant subcommittee of the Service’s Great Lakes
Ecosystem Team, with involvement by State fish and wildlife agency personnel, has
produced a cormorant fact sheet series. Additionally, the Service provided funding and
production assistance to New York Sea Grant to produce the video “Managing
Cormorants in the Great Lakes.”
Service personnel have attended numerous public workshops pertaining to DCCOs and
their management, often participating with State fish and wildlife agency personnel. In
1997, the Service, together with APHIS/WS, organized a symposium on the biology and
11 – Chapter 1
management of DCCOs in the Midwest and published the proceedings (Tobin 2000). In
November 2000, the Service cooperated with University of Minnesota researchers in
putting together a one-day workshop on the DCCO-fisheries conflict, which brought
together biologists and managers from around the nation and the world. Service
personnel have also accepted many invitations to speak to citizens around the U.S. who
are interested in cormorants and the Service’s role in managing migratory birds.
1.4.5 The Role of Other Agencies in Cormorant Management
Because DCCOs fall under the authority of the MBTA, the Service has the primary
responsibility for establishing guidelines for the take of cormorants. Consequently,
management options available to States and other agencies are limited by our policies and
practices. However, some States have been and continue to be actively engaged in
research activities and the implementation of management activities authorized by the
Service.
Control Activities. A survey completed by Wires et al. (2001) found that 10 States (out of
37 States and provinces that responded to the survey) reported the use of DCCO control
methods. Six of the States employing control measures were in the southern U.S.; these
States were conducting control programs because of depredations at aquaculture facilities
and fish hatcheries. All of these States incorporated lethal and non-lethal control
measures. In the Northeast, New York and Vermont are employing control measures due
to habitat destruction and impacts to other colonial waterbirds in Lake Ontario and Lake
Champlain. Massachusetts has undertaken limited control measures at specific sites.
Additionally, the State of Oregon conducts annual DCCO harassment programs near the
Oregon coast.
Table 1. States Practicing DCCO Control (from Wires et al. 2001)
State Lethal measures Non-lethal measures
AL Shooting Harassment
AR Shooting Harassment, noise-making, decoys
LA Shooting Multiple harassment techniques
MA None Harassment
MS Shooting Harassment; Night roost dispersal program
NY Egg destruction, egg oiling Nest destruction
OK Shooting Hazing
TX Shooting Harassment
VA Yes1 Yes1
VT Egg oiling Harassment; nest destruction
1 Both lethal and non-lethal measures are undertaken, but details on specific measures employed were not
provided.
DCCOs also occur in Canada and Mexico. In Canada, DCCOs are not protected
federally and thus are managed at the provincial level. The Province of Québec has
conducted limited DCCO population control and Ontario is in the process of evaluating
the need for such action. As in the U.S., Canadian DCCO populations are generally
increasing. We are currently unaware of any involvement by Mexico in management of
DCCOs. The precise status of DCCO populations in Mexico is unknown but probably
12 – Chapter 1
stable (Wires et al. 2001). It was last estimated by Carter et al. (1995b) at about 6,969
breeding pairs.
13 – Chapter 2
CHAPTER 2: ALTERNATIVES
2.1 Introduction
This chapter, considered the “heart of the environmental impact statement” (40 CFR
1502.14), describes the six alternatives being evaluated for the purpose of managing
DCCOs in the contiguous United States. It also states the “proposed action” (Alternative
D), which is our preferred alternative for meeting the purpose and need stated in Chapter
1.
2.2 Rationale for Alternative Design
All alternatives considered were evaluated in relation to their ability to reduce resource
conflicts associated with DCCOs, increase management flexibility, and conserve healthy
populations of DCCOs over the long term. NEPA regulations require the analysis of a
No Action (or “status quo”) alternative. The other alternatives were developed after
evaluating comments received during the public scoping period, holding interagency
meetings and internal discussions, and reviewing the best available information. After
the DEIS public comment period, we discussed and developed changes to the proposed
action to improve its potential for efficacy in dealing with cormorant conflicts and in
ensuring the conservation of populations of DCCOs and other Federally-protected
species. Each alternative described below is analyzed in more detail in Chapter 4,
ENVIRONMENTAL CONSEQUENCES.
2.3 Proposed Action
The agency’s proposed action is the alternative that the agency believes would satisfy the
purpose and need (as stated in Chapter 1) and fulfill its mission and statutory
responsibilities, while giving consideration to economic, environmental, technical, and
other factors. The proposed action, Alternative D, would: (1) create a public resource
depredation order to authorize State fish and wildlife agencies, Tribes, and APHIS/WS in
24 States to control DCCOs on public and private lands and freshwaters to protect public
resources; (2) expand the aquaculture depredation order to allow winter roost control by
APHIS/WS in 13 States; and (3) allow take of DCCOs at public fish hatcheries under the
depredation orders. Based on our analysis, the proposed action would be more effective
than the current program; is environmentally sound, cost effective, and flexible enough to
meet different management needs around the country; and does not threaten the long-term
sustainability of DCCO populations or populations of any other natural resource.
2.4 Description of Alternatives
2.4.1 Alternative A: No Action (Continue existing DCCO damage management
policies)
Under this alternative, existing wildlife management policies and practices would
continue with no additional regulatory methods or strategies being authorized. This
alternative includes non-lethal management techniques (as described under Alternative
B) and activities carried out under depredation permits and the aquaculture depredation
order. Control techniques include the take of adults and young (by shooting), eggs (by
means of oiling or destruction), and active nests (by removal or destruction). Because of
Director’s Order No. 27, “Issuance of Permits to Kill Depredating Migratory Birds at
14 – Chapter 2
Fish Cultural Facilities,” depredation permits are not issued for the take of DCCOs at
National Fish Hatcheries. However, the aquaculture depredation order allows DCCOs to
be killed at State-operated fish hatcheries in 13 States (and at commercial freshwater
aquaculture facilities). All other conflicts are dealt with on a case-by-case basis,
requiring a Federal permit for every locality and occurrence where DCCO control actions
take place. All depredation permits would continue to be issued by the appropriate
Service Regional Office. Population surveys on breeding grounds would continue to be
conducted at regular intervals.
The issuance of depredation permits to take cormorants and other depredating migratory
birds is guided by the regulations found in 50 CFR §21.41. There it states that an
application for a depredation permit must be submitted to the appropriate Service
Regional Director and that each application must contain a description of the area where
depredations are occurring; the nature of the crops or other interests being injured; the
extent of such injury; and the particular species of migratory birds committing the injury.
The following table describes how the Service Regional Migratory Bird Permit Offices
have interpreted 50 CFR §21.41 and §21.47 for various resource categories.
15 – Chapter 2
Table 2. Service Practice for Issuance of Depredation Permits for DCCOs under
Alternative A (No Action)
Aquaculture
Private and State facilities in 13 States do not require a permit because they fall under the aquaculture
depredation order (AL, AR, FL, GA, KY, LA, MN, MS, NC, OK, SC, TN, and TX).
In States not covered by the depredation order APHIS/WS makes recommendations and USFWS issues
permits to take birds, eggs, and/or active nests.
Director’s Order No. 27 prohibits lethal control of fish-eating birds at “public” hatcheries except when an
“emergency” exists.
Natural Resource Issues on Public Lands/Waters
Permits issued by USFWS when action is considered necessary to ensure survival and/or recovery of
Federal- or State-listed threatened and endangered species.
Permits may be issued by USFWS if there exists convincing evidence that a regionally significant bird
population or rare and declining plant communities are being adversely affected by DCCOs.
Permits may be issued by USFWS to alleviate depredation at the site of fish stocking but requests for
permits are generally not issued for birds taking free-swimming fish in public waters.
Other Natural Resource and Economic Issues
Permits may be issued by USFWS if there is significant economic damage to privately-stocked fish on a
privately-owned water body that maximizes fishing opportunities for patrons, whether done for a fee or
for recreation.
Permits typically issued by USFWS for significant property damage (for example, physical structures or
vegetation) on public or private lands and waters.
Human Health and Safety
Permits issued by USFWS when evidence exists of significant human health and safety risks (for
example, airports or water quality).
2.4.2 Alternative B: Non-lethal Management (Do not allow lethal management
actions)
Under this alternative, permits allowing the lethal take of DCCOs or their eggs would not
be issued. The aquaculture depredation order would be revoked and depredation permits
would not be issued. To reduce impacts associated with DCCOs, this option would allow
only non-lethal management techniques such as harassment, habitat modification,
exclusion devices at production facilities, and changes in fish stocking practices.
Essentially, only those management techniques not currently requiring a Federal
depredation permit would be continued under this alternative. Population surveys would
be conducted at regular intervals.
16 – Chapter 2
2.4.3 Alternative C: Increased Local Damage Control (Expand current wildlife
damage management policy)
The intent of this alternative would be to expand the current DCCO depredation policy to
address a broader range of resource conflicts than under the No Action (see Table 3
below). The permit renewal period for DCCO depredation permits would change from
annual to biennial in order to help alleviate the increased permit review requirements
(this means that permittees would reapply for a permit every two years instead of each
year). The aquaculture depredation order would continue to allow DCCOs to be killed at
commercial freshwater aquaculture facilities and State-owned fish hatcheries in 13 States
and would be expanded to include winter roost control at aquacultural facilities in those
States. Director’s Order No. 27 prohibiting lethal control of DCCOs at public fish
hatcheries would be revoked. Non-lethal techniques would remain part of the
management program. Population surveys would be conducted at regular intervals.
17 – Chapter 2
Table 3. Service Policy for Issuance of Depredation Permits for DCCOs under
Alternative C
Aquaculture
Private and State facilities in 13 States do not require a permit because they fall under the aquaculture depredation
order (AL, AR, FL, GA, KY, LA, MN, MS, NC, OK, SC, TN, and TX). (Same as No Action)
In States not covered by the depredation order APHIS/WS makes recommendations for permit issuance and
USFWS may issue permit to take birds, eggs, and/or active nests. (Same as No Action)
Aquaculture depredation order expanded to include lethal control at winter roost sites in those 13 States. (Different
than No Action)
Director’s Order No. 27 prohibiting lethal take at public hatcheries revoked. (Different than No Action)
Natural Resource Issues on Public Lands/Waters
Permits issued by USFWS when action is considered necessary to ensure survival and/or recovery of Federal- or
State-listed threatened and endangered species. (Same as No Action)
Permits issued by USFWS for conflicts with fish, wildlife, plants, and other wild species when there is
documentation of significant impacts or when best professional judgment has determined that there is a high
likelihood that DCCOs are a significant detriment to the resource in question. In the latter case, a permit will be
issued when the control efforts will not threaten the viability of DCCO or other wildlife populations and the agency
requesting the permit prepares a site-specific management plan containing: (1) a definition of the conflict(s) with
DCCOs, including a statement of the management objectives for the area in question; (2) a description of the
evidence supporting the hypothesis that DCCOs are contributing to these resource conflicts; (3) a discussion of
other limiting factors affecting the resource (e.g., biological, environmental, socioeconomic); and (4) a discussion
of how control efforts are expected to alleviate resource conflicts. (Different than No Action)
Other Natural Resource and Economic Issues
Permits issued by USFWS if there is significant economic damage to privately-stocked fish on a privately-owned
water body that maximizes fishing opportunities for patrons, whether done for a fee or for recreation. (Same as No
Action)
Permits issued by USFWS for significant property damage (for example, physical structures or vegetation) on
public or private lands and waters. (Same as No Action)
Human Health and Safety
Permits issued by USFWS when evidence exists of significant human health and safety risks (for example, airports
water quality). (Same as No Action)
2.4.4 PROPOSED ACTION – Alternative D: Public Resource Depredation Order
(Establish a new depredation order to address public resource conflicts)
Alternative D creates a public resource depredation order to authorize State fish and
wildlife agencies, Federally-recognized Tribes, and APHIS/WS to take DCCOs found
committing or about to commit, and to prevent, depredations on the public resources of
fish (including hatchery stock at Federal, State, and Tribal facilities), wildlife, plants, and
their habitats. This authority applies to all lands and freshwaters (with appropriate
landowner permission) in 24 States (Alabama, Arkansas, Florida, Georgia, Illinois,
Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi,
18 – Chapter 2
Missouri, New York, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee,
Texas, Vermont, West Virginia, and Wisconsin). This alternative also revises the
aquaculture depredation order by specifying that it is applicable to commercial freshwater
facilities and State and Federal fish hatcheries, and by authorizing APHIS/WS employees
to take DCCOs at roost sites in the vicinity of aquaculture facilities during the months of
October, November, December, January, February, March, and April. Director’s Order
No. 27 prohibiting lethal control of DCCOs at public hatcheries will not be revoked at
this time, as was stated in the DEIS. Depredation permits would continue to be used to
address conflicts outside the authority of the depredation orders. Agencies acting under
the public resource depredation order will be required to comply with monitoring and
reporting requirements and persons operating under the aquaculture depredation order
must annually provide a current mortality log. Population surveys will be conducted at
regular intervals.
Table 4. Service Depredation Policy under Alternative D (PROPOSED ACTION)
Aquaculture
Private, State, and Federal facilities in 13 States do not require a permit because they fall under the
aquaculture depredation order. (Different than No Action)
In States not covered by the depredation order APHIS/WS makes recommendations for permit issuance and
USFWS may issue permit to take birds, eggs, and/or active nests. (Same as No Action)
Aquaculture depredation order expanded to include lethal control at winter roost sites in 13 States.
(Different than No Action)
Natural Resource and Economic Issues on Public Lands/Waters
In 24 States, State fish and wildlife agencies, Tribes, and APHIS/WS may take DCCOs to protect public
resources (fish, wildlife, plants, and their habitats) on private and public lands and freshwaters. In non-depredation
order States, depredation permits for public resource damages will be issued in accordance
with 50 CFR 21.41 and applicable Service policies. (Different than No Action)
Permits issued by USFWS for significant property damage (for example, to physical structures or
vegetation) on public or private lands and waters. (Same as No Action)
Human Health and Safety
Permits issued by USFWS when evidence exists of significant human health and safety risks (for example,
at airports or when water quality is compromised). (Same as No Action)
2.4.5 Alternative E: Regional Population Reduction (Develop population objectives
and implement actions aimed at reducing overall DCCO populations)
This alternative would entail the development of regional DCCO population objectives
designed to reduce damages associated with DCCOs. Population objectives would be
developed on an interdisciplinary, interagency basis and would be based on the best
available data, while giving consideration to other values. Control would be carried out
at nesting, roosting, wintering and all other sites in order to achieve those objectives as
rapidly as possible without adversely affecting other protected migratory birds or
threatened and endangered species. The aquaculture depredation order would allow
DCCOs to be killed at commercial freshwater aquaculture facilities and Federal, State,
and Tribal fish hatcheries in 13 States and would be expanded to include winter roost
control in those States. For all conflicts not addressed under the aquaculture depredation
Comment:
19 – Chapter 2
order or the special statewide cormorant permit, depredation permits would be issued
according to the policy outlined in Alternative C above. Non-lethal techniques would
remain part of the management program, but only voluntarily. Population surveys would
be conducted at regular intervals.
2.4.6 Alternative F: Regulated Hunting (Establish frameworks for a hunting season
on DCCOs)
Under this alternative, frameworks to develop seasons and bag limits for hunting DCCOs
would be established jointly by Federal and State wildlife agencies. These seasons would
coincide with those for waterfowl hunting. Additionally, the depredation policy outlined
in Alternative C, above, would address DCCO conflicts (issuance of depredation permits
and the aquaculture depredation order). Population monitoring would be conducted at
regular intervals.
2.5 Alternatives Considered but Eliminated from Detailed Study
2.5.1 No Management Alternative
This alternative would not allow for any Federal management or control of DCCOs (no
depredation permit issuance, no depredation order, no harassment or habitat modification,
etc.). To implement this alternative would be to ignore conflicts associated with
cormorants that must be addressed if we are to fulfill our duties to manage America’s
migratory birds responsibly. Since there is real biological and socioeconomic evidence
(as described in Chapter 3, AFFECTED ENVIRONMENT) justifying the need for
DCCO management, we find this alternative to be unreasonable (NEPA states that only
“reasonable” alternatives must be considered).
2.5.2 Rescindment of Migratory Bird Treaty Act Protection Alternative
This alternative would entail amending the MBTA and associated international
conventions to remove the DCCO from the List of Migratory Birds (those species
protected under the MBTA). DCCOs would still be protected under the laws of most
States. This action would require amending the Mexican treaty and could have the
undesirable result of losing protection for all species in the cormorant family
(Phalacrocoracidae). We feel that this would be a drastic action that would establish
precedent for removing other species and would undermine the authority of the MBTA.
2.6 Comparison of Alternatives
Each alternative described above would utilize a variety of non-lethal management
techniques. All of the alternatives we analyzed, except Alternative B, would allow for
limited lethal take (shooting, egg oiling or destruction, and/or nest destruction), either
through depredation orders or the issuance of depredation permits. Additionally,
Alternative F would develop hunting frameworks for DCCOs. Differences among
alternatives in the degree of lethal take are primarily related to the circumstances under
which permits are issued (to control local damages or to reach population objectives) and
which depredation order is in effect (aquaculture, expanded aquaculture, and/or public
resource).
20 – Chapter 2
Table 5. Actions by Alternative
Alternative Actions
Alternative A – No Action non-lethal management¹; aquaculture depredation order²;
depredation permits³
Alternative B – Non-lethal
management
non-lethal management1
Alternative C – Increased Local
Damage Control
non-lethal management1; expanded aquaculture depredation order2;
depredation permits3
Alternative D – PROPOSED
ACTION
non-lethal management1; expanded aquaculture depredation order2;
depredation permits3; public resource depredation order4
Alternative E – Regional
Population Reduction
non-lethal management1; expanded aquaculture depredation order2;
depredation permits3
Alternative F – Regulated Hunting non-lethal management1; aquaculture depredation order2;
depredation permits3, hunting seasons in participating States
¹ = includes all management techniques that are not considered “take” and thus do not
require a depredation permit (harassment, exclusion devices, habitat modification, etc.)
² = under the aquaculture depredation order, DCCOs may be taken by shooting with
firearms during daylight hours; those using shotguns are required to use nontoxic shot
³ = under depredation permits, shooting, egg oiling or destruction, and nest destruction
are the most common techniques utilized
4 = under the public resource depredation order, DCCOs may be taken by shooting, egg
oiling or destruction, nest destruction, cervical dislocation, and CO2 asphyxiation (all of
which are classified as humane euthanasia techniques for birds by the American
Veterinary Medical Association)
21 – Chapter 2
Table 6. Actions by Alternatives
A: No
Action
B: Non-lethal
Management
C:
Increased
Local
Damage
Control
PROPOSED
ACTION
D: Public
Resource
Depredation
Order
E:
Regional
Population
Reduction
F:
Regulated
Hunting
New regulatory
strategies no no no yes yes yes
Continued issuance of
depredation permits yes no yes yes yes yes
Continuation of
aquaculture depredation
order yes no yes yes yes yes
Expansion of
aquaculture depredation
order no no yes yes yes yes
Creation of public
resource depredation
order no no no yes no no
Allows take of nests yes yes yes yes yes yes
Allows take of eggs yes no yes yes yes yes
Allows take of adults
and young yes no yes yes yes yes
Allows harassment of
adults and young yes yes yes yes yes yes
Development of
regional population
objectives no no no maybe yes no
Management activities
occur on public lands yes yes yes yes yes yes
Management activities
occur on private lands yes yes yes yes yes yes
Requires additional
monitoring and
evaluation no no no yes yes yes
22 – Ch apter 3
CHAPTER 3: AFFECTED ENVIRONMENT
3.1 Introduction
The “affected environment” section of an EIS should “succinctly describe the
environment of the area(s) to be affected by the alternatives under consideration” (40
CFR 1502.15). Thus, this chapter contains a discussion of the biological and
socioeconomic environments relevant to the issues raised during scoping.
3.2 Biological Environment
3.2.1 Double-crested Cormorants
The Service’s goals in migratory bird management are to conserve DCCO populations at
sufficient levels to prevent them from becoming threatened or endangered and to ensure
that American citizens have continued opportunities to enjoy DCCOs.
Species Range. DCCOs are native to North America and range widely there. There are
essentially five different breeding populations, variously described by different authors
as: Alaska, Pacific Coast, Interior, Atlantic, and Southern. Recent population expansion,
however, has blurred the boundaries for the Interior, Atlantic, and Southern populations
(Hatch and Weseloh 1999, Wires et al. 2001). There is high variation in the migratory
tendencies of these different breeding populations. Birds that breed in Florida and
elsewhere in the Southeastern U.S. are essentially sedentary, those along the Pacific coast
are only slightly migratory, while Atlantic and Interior birds show the greatest seasonal
movements (Johnsgard 1993). The two primary migration routes appear to be down the
Atlantic coast and through the Mississippi-Missouri River valleys to the Gulf coast
(Palmer 1962) with increasing numbers of birds remaining in the Mississippi Delta
(Jackson and Jackson 1995). Refer to Appendix 2 for a map of the distribution of DCCO
breeding colonies in North America.
Habitat Requirements. In the breeding season, two factors are critical to DCCOs: suitable
nesting sites and nearby feeding grounds (van Eerden and Gregersen 1995, Hatch and
Weseloh 1999, Wires et al. 2001). Ponds, lakes, slow-moving rivers, lagoons, estuaries
and open coastlines are utilized. Small rocky or sandy islands are utilized when
available. Nests are built in trees, on structures, or on the ground. Nesting trees and
structures are usually standing in or near water, on islands, in swamps, or at tree-lined
lakes.
Nonbreeding habitats are diverse and include lakes, ponds, rivers, lagoons, estuaries,
coastal bays, marine islands, and open coastlines (Johnsgard 1993). Wintering DCCOs
require similar characteristics in feeding, loafing, and roosting sites as when breeding.
Where DCCOs winter on the coast, sandbars, shoals, coastal cliffs, offshore rocks,
channel markers, and pilings are used for roosting. Birds wintering along the lower
Mississippi River roost on perching sites such as trees, utility poles, or fishing piers and
in isolated cypress swamps (Reinhold and Sloan 1999, Wires et al. 2001). In all seasons
DCCOs require suitable places for nighttime roosts and daytime resting or loafing.
Roosts and resting places are often on exposed sites such as rocks or sandbars, pilings,
wrecks, high-tension wires, or trees near favored fishing locations (Wires et al. 2001).
23 – Ch apter 3
From the time DCCOs return to their breeding colonies in the spring until the adults are
brooding young, the colony site is their main “center of activity,” (i.e., they roost at the
colony overnight and their daily foraging activities emanate from there). While most
adults are attending young, however, auxiliary overnight roosts begin to develop. These
may be on nearby unoccupied islands or they may be several miles away. The origin of
the birds forming these roosts is not known for certain but they are most likely adults who
have failed in their breeding attempts and/or non-breeding birds. The net result is that a
new or additional “center of activity” is created in an area where the birds themselves do
not otherwise breed. These late season roosts often remain active until the birds have left
on migration in September or October. For example, DCCOs do not breed in the Bay of
Quinte, a 60 mile-long, Z-shaped bay in northeastern Lake Ontario. However, in June,
well before the migratory season, DCCOs begin to roost, at night, on islands in the bay
and their numbers increase there through September. Birds come from these islands on
daily foraging trips and have, in essence, established new centers of activity that are not
related to the breeding colony, nor are they (yet) comprised of migrant birds (D.V.
Weseloh, CWS, pers. comm.).
Double-crested Cormorant Demographics. The DCCO is the most abundant of five
species of cormorants occurring in the contiguous United States (the other species are
Great Cormorant, Neotropic Cormorant, Pelagic Cormorant, and Brandt’s Cormorant). A
conservative estimate of the total population of DCCOs in the U.S. and Canada is greater
than 1 million birds, including breeding and non-breeding individuals, but is probably
closer to 2 million (Tyson et al. 1999). We estimate that the current continental
population of DCCOs is approximately 2 million birds. This number was derived by
consulting the literature and discussing our estimate with waterbird biologists Linda
Wires (University of Minnesota), Dr. Francie Cuthbert (University of Minnesota), Dr.
Chip Weseloh (Canadian Wildlife Service), and John Trapp (USFWS). We used the
Tyson et al. estimate of 372,400 breeding pairs as our base number. We multiplied that
by 2 to get the number of breeding individuals (744,280). Then we multiplied that by
2.26, an estimate for the ratio of non-breeding to breeding birds (Weseloh unpubl. data)
that is well within the published estimates ranging from 1-4 nonbreeders per breeder).
This amounts to 1,682,073 and adding that to 744,280 comes to 2,426,353 birds total. In
2000, Chip Weseloh (unpubl. data) estimated the North American population for
breeding and non-breeding immature DCCOs (but not adult non-breeders) at 1.850
million. Based on this information and discussions with the individuals mentioned
above, we adjusted our estimate of 2.4 million to 2.0 million.
While the total number of DCCOs in North America increased rapidly from the 1970s
into the 1990s (Hatch 1995), estimates of Tyson et al. (1999) indicated that the overall
rate of growth in the U.S. and Canada slowed during the early 1990s. This is consistent
with declines in the growth rate of expanding Great Cormorant populations in
northwestern Europe (van Eerden and Gregersen 1995) and with the general rule that the
growth rate of wildlife populations decreases as it gets closer to carrying capacity.
24 – Ch apter 3
For the U.S. as a whole, according to Breeding Bird Survey (BBS) data (which are
indices of relative abundance), the breeding population of DCCOs increased at a
statistically significant rate of approximately 7.5 percent per year from 1975-2002 (Sauer
et al. 2003). Within this period, growth rates of regional populations varied substantially
and thus it is important to look at DCCO population growth rates from a regional
perspective as well. The table below summarizes the regional populations as described in
Tyson et al. 1999. The narratives that follow integrate the populations delineations used
by Tyson et al. 1999 and Wires et al. 2001. See Appendix 2 for the distribution of DCCO
breeding colonies in North America.
Table 7. DCCO Breeding Population Estimates (from Tyson et al. 1999)
Estimated # of nesting
pairs
Percent of continental
population
Estimated population
growth rate *
Atlantic 85,510 23% -6.5% (15.8%)
Interior 256,212 68% 6.0% (20.8%)
Southeast 13,604 4% 2.6% (76.9%)
West Coast-Alaska 17,084 5% -7.9% (-0.6%)
TOTAL > or = 372,410 2.6% (16.2%)
* number in parentheses indicates “category A” estimates (i.e., results of surveys in which nests were
systematically counted)
Atlantic
Twenty-three percent of North America’s DCCOs are found in the Atlantic population
(Tyson et al. 1999). In this region, DCCOs are strongly migratory and, on the coast,
occur with smaller numbers of Great Cormorants. From the early 1970s to the early
1990s, the Atlantic population increased from about 25,000 pairs to 96,000 pairs (Hatch
1995). While the number of DCCOs in this region declined by 6.5 percent overall in the
early to mid-1990s, some populations were still increasing during this period (Tyson et
al. 1999). Very large numbers breed in Quebec and the surrounding area (including the
St. Lawrence River and its estuary) and in Nova Scotia and Prince Edward Island. Very
large breeding concentrations also occur in New England along the coasts of Maine and
Massachusetts. With the exception of Maine (where numbers began declining between
the mid-1980s and early 1990s), rapid increases have occurred since the 1970s (Wires et
al. 2001). From 1977 to the 1990s, the number of DCCOs in the northeastern U.S.
increased from 17,100 nesting pairs to 34,200 pairs (Krohn et al. 1995). In parts of
southern New England (Connecticut, Rhode Island, coastal New York) the DCCO has
recently been documented as a breeding species and numbers are growing fairly rapidly.
First breeding records were obtained in New Jersey and Pennsylvania between the late
1970s and 1990s (Wires et al. 2001). The total estimated number of nesting pairs in this
population is $85,510 (Tyson et al. 1999).
Small numbers of DCCOs winter in some New England States but most Atlantic birds
winter along the coast from Virginia (where numbers of wintering birds are increasing)
southward, along the Gulf of Mexico, and in the lower Mississippi valley (Dolbeer 1991,
Hatch 1995, Wires et al. 2001).
25 – Ch apter 3
Interior
Nearly 70 percent of North American DCCOs are found in the Interior region (Tyson et
al. 1999). DCCOs in this region are highly migratory and are concentrated in the
northern prairies, particularly on the large, shallow lakes of Manitoba (Canada), which
has the largest number of breeding DCCOs in North America (Hatch 1995, Wires et al.
2001). A large number of Interior DCCOs nest on or around the Great Lakes as well, and
recent evidence indicates that they are beginning to establish themselves at small inland
lakes in the vicinity (Alvo et al. 2002). Since the early 1970s, numbers of Interior
DCCOs have increased rapidly.
From 1990 to 1997, the overall growth rate in the Interior region was estimated at 6
percent (Tyson et al. 1999) with the most dramatic increases occurring on Ontario,
Michigan, and Wisconsin waters (Wires et al. 2001). From 1970 to 1991, the Great
Lakes breeding population alone increased from 89 nests to over 38,000 nests, an average
annual increase of 29 percent (Weseloh et al. 1995). From 1991 to 1997, the number of
nests in the Great Lakes further increased to approximately 93,000, an average annual
increase of 22 percent. Nest counts in 2000 estimated 115,000 nests in the Great Lakes
(Weseloh et al. 2002). Average annual growth rates in the Great Lakes were lower for
the period 1990-2000 than the period 1980-1990 (Weseloh et al. 2002). The total
estimated number of nesting pairs in the Interior population (including Canada) is
$256,212 (Tyson et al. 1999).
Southern
Most DCCOs in this region are wintering migrants from the Interior and Atlantic regions
(Dolbeer 1991, Jackson and Jackson 1995). However, nesting DCCOs in this region are
on the rise with some nesting occurrences representing first record and others
recolonizations (Wires et al. 2001). Historically, sedentary breeding populations of
DCCOs occurred in Florida and other southern states north to North Carolina (Hatch
1995), while in recent years DCCOs have started breeding again in Arkansas, Georgia,
Mississippi, and Tennessee (Wires et al. 2001). Today, four percent of the North
American breeding population of DCCOs occurs in the Southeast region (Tyson et al.
1999). Currently, breeding colonies exist in Arkansas, Delaware, Florida, Georgia,
Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennesee, Texas, and
Virginia (Wires et al. 2001). The total estimated number of nesting pairs in this
population is >13,604 (Tyson et al. 1999).
Over the last few decades, numbers of wintering DCCOs have dramatically increased in
several southern States. Since the late 1970s, wintering DCCOs have increased by nearly
225 percent since the early 1990s in the Mississippi Delta. From an average of 30,000
DCCOs counted during the winters of 1989-93 (Glahn et al. 1996) to over 73,000
counted in the winter of 2001-2002 (G. Ellis, APHIS/WS, unpubl. data). Data from
Christmas Bird Counts conducted between 1959-1988 show increases ranging from 3.5-
18.7 percent in several States within this region, with the largest increases occurring in
Louisiana, Mississippi, and Texas (Wires et al. 2001). In New Mexico, Texas, and
Louisiana DCCOs overlap in range with Neotropic Cormorants.
26 – Ch apter 3
Pacific Coast-Alaska
Approximately 5-7 percent of North America=s DCCOs are found in this population,
which has approximately 27,500 nesting pairs according to Carter et al. (1995b) or
>17,084 pairs according to Tyson et al. (1999). Alaska DCCOs represent approximately
12 percent of the entire Pacific coast marine population (Carter et al. 1995b) and occur
with Red-faced Cormorants. Throughout their coastal range DCCOs exist with larger
numbers of Pelagic and Brandt=s Cormorants and at the southern extent of their range in
Mexico they occur with Neotropic Cormorants (Hatch 1995). Alaska breeding
populations (P. a. cincinatus) are thought to have declined since historical times, but
recent population trends are not known (Wires et al. 2001). Non-Alaska Pacific coast
breeding DCCOs (P. a. albociliatus) occur from British Columbia through Sinaloa,
Mexico. Historical declines throughout the range are well documented and recent
population status and trends for coastal populations, from British Columbia through
California, are reasonably complete. However, because recent data are not available for
significant portions of this subspecies range (e.g., Mexico and some interior areas) it is
not possible to summarize recent trends for the population as a whole. Carter et al.
(1995) documented recent increases in California and Oregon, and declines in British
Columbia, Washington, and Baja California. Tyson et al. (1999) did not consider
Mexican populations and calculated a decline for the entire West Coast-Alaska region. In
the past 20 years, the largest increases in the region have taken place in the Columbia
River Estuary, where East Sand Island supports the largest active colony along the coast
with 6,390 pairs in 2000 (Carter et al. 1995b, Collis et al. 2000, Wires et al. 2001).
Increases at East Sand Island coincided with declines in British Columbia, Washington,
and locations in interior Oregon and the rapid increase undoubtedly reflected some
immigration from these other areas (Carter et al. 1995).
Another area of recent explosive population increase is Salton Sea, California. Complete
surveys of interior California populations were conducted between 1997-1999 (Shuford
2002). Shuford estimated 6,825 pairs breeding at 29 active colonies and 80 percent of all
interior pairs occurred at Salton Sea. DCCOs at Salton Sea, increased from zero (1990-
1994) to 5,600 pairs in 1999, and then back to zero from 2001 through 2003 (Shuford
2002, C. Pelizza pers. comm.).
Factors associated with population increases. Factors contributing to the resurgence of
DCCO populations include reduced levels of environmental contaminants, particularly
DDT; increased food availability in breeding and wintering areas; and reduced human
persecution (Ludwig 1984, Vermeer and Rankin 1984, Price and Weseloh 1986, Fox and
Weseloh 1987, Hobson et al. 1989, Weseloh et al. 1995, Wires et al. 2001). A brief case
study of DCCOs in the Great Lakes provides an example of factors associated with
changes in DCCO population numbers:
In the early 1940s, DCCO populations in the American and Canadian Great Lakes were increasing rapidly
(Postupalsky 1978, Weseloh et al. 1995). After 1945, however, organochlorine pesticides came to be
widely used in the Great Lakes basin. The residues of such chemicals, particularly DDT, are ecologically
persistent and rapidly bioaccumulate in the aquatic food web, and this led to severe eggshell thinning in
DCCOs and other waterbirds. Cormorant eggs with thinned shells broke easily during incubation and led
to a period, in the 1950s and 1960s, of almost zero productivity due to low hatching success (Postupalsky
1978, Weseloh et al. 1983, Weseloh et al. 1995). Similar eggshell thinning and reproductive failure were
27 – Ch apter 3
also found in DCCOs in southern California in the late 1960s (Gress et al. 1973). Following restrictions on
the use of DDT in 1972, levels of organocholorine contaminants found in DCCO eggs declined in much of
the Great Lakes (Ryckman et al. 1998) and DCCO productivity increased accordingly during the late 1970s
(Scharf and Shugart 1981, Ludwig 1984, Noble and Elliot 1986, Price and Weseloh 1986, Bishop et al.
1992a and b). Organochlorine contaminant-related eggshell thinning no longer appears to be a major
limiting factor for DCCO reproduction on the Great Lakes (Ryckman et al. 1998), even though there are
still lingering effects of these chemicals in parts of this ecosystem three decades after they were banned
(Custer et al. 1999).
Changes in the food supply available to Great Lakes cormorants, on both the breeding
and wintering grounds, have also played a role in their population increase. Great Lakes
fish populations underwent major changes in the 20th century. Populations of forage fish
species increased significantly during the late 1950s through the 1980s, likely as a result
of dramatic declines in large, native predatory fish, such as lake trout and burbot, that
occurred during the 1940s and 1950s. These declines in larger predatory fish were
brought about by a combination of such factors as overfishing, sea lamprey predation,
and loss of spawning habitat (Weseloh et al. 1995) and led to population explosions of
smaller forage fish species. In particular, rainbow smelt and alewife, neither of which are
native to the upper Great Lakes, became very abundant in Lakes Michigan, Huron,
Ontario, and Erie through the 1970s and 1980s (Environment Canada 1995). Various
studies suggest that annual productivity and post-fledging survival of DCCO young are
high in years of alewife abundance (Palmer 1962; van der Veen 1973, Weseloh and
Ewins 1994). In fact, changes in prey abundance have been associated with increases in
populations of several fish-eating bird species worldwide (Environment Canada 1995).
The growth of the aquaculture industry has provided DCCOs with an abundant food
supply on their southern wintering grounds. The aquaculture industry (consisting largely
of channel catfish production) has experienced significant growth in the southern U.S.
over the last 20 years. While Great Lakes DCCOs historically migrated down to the
coastal areas of the Gulf of Mexico to winter, since the early 1970s wintering populations
of DCCOs in the lower Mississippi valley have been increasing (Reinhold and Sloan
1999, Glahn et al. 1996). The DCCO is the primary avian predator utilizing channel
catfish stocks (Wywialowski 1998, Reinhold and Sloan 1999). Glahn et al. (1999b)
analyzed monthly changes in body mass of wintering DCCOs in the delta region of
Mississippi and in areas without extensive aquaculture production and found that DCCO
utilization of catfish has likely increased winter survival and contributed to the
cormorant’s recent population resurgence.
Human persecution has also been a factor. DCCOs were not Federally protected until
1972. Weseloh et al. (1995) suggested that the cormorant’s initial rate of colonization
into the Great Lakes was suppressed by human persecution until the 1950s. Indeed,
destruction of DCCO nests, eggs, young, and adults, by fishermen and government
agencies, was a common occurrence in the Great Lakes basin from the 1940s into the
1960s (Baillie 1947, Omand 1947, Postupalsky 1978, Ludwig 1984, Craven and Lev
1987, Ludwig et al. 1989, Weseloh and Ewins 1994, Weseloh et al. 1995, Matteson et al.
1999) and in the Pacific Northwest (Gabrielson and Jewett 1940, Ferris 1940, Mathewson
1986, Bayer and Ferris 1987, Carter et al. 1995a). Similar control efforts, involving
large-scale spraying of eggs, occurred in Maine in the 1940s and 1950s (Gross 1951,
28 – Ch apter 3
Krohn et al. 1995, Hatch 1995) and in Manitoba on Lake Winnipegosis during the same
period (McLeod and Bondar 1953, Hatch 1995). In 1972, DCCOs were added to the list
of birds protected by the MBTA, which made it illegal to kill them in the U.S. without a
Federal permit.
Double-crested Cormorant Population Parameters. Compared to other common colonial
waterbirds, the population dynamics of DCCOs have not been well-studied (Wires et al.
2001, Hatch and Weseloh 1999). The similar life histories of DCCOs and Great
Cormorants (i.e., their being ecological counterparts), however, allow North American
managers to gain insight from management efforts in Europe (Glahn et al. 2000b). Due
to their large clutch size and persistent renesting efforts, DCCO breeding success is fairly
high compared to other North American cormorants and colonial waterbirds in general
(Johnsgard 1993).
Age at First Breeding
Van der Veen (1973) found that most birds bred for the first time at age 3 (i.e., entering
their fourth year). Johnsgard (1993, citing van Tets in Palmer 1962) also stated that “the
usual age of initial breeding in this species is probably three years, although successful
breeding has occurred among two-year-olds.” In the early 1990s, Weseloh and Ewins
(1994) observed first-breeding by many 2-year olds on Little Galloo Island in Lake
Ontario. Blackwell et al. (2002) estimated that at least 17 percent of 2-year old, and 98.4
percent of age-3+, Lake Ontario DCCOs breed.
Clutch Size
Average clutch sizes observed over the years include: 3.8 eggs in Utah (Mitchell 1977);
3.5 eggs in Maine (Mendall 1936); 3.11 eggs in Ontario (Peck and James 1983); 3.2 eggs
in Alberta (Vermeer 1969); 3.6 and 3.2 on the Madeleine Islands in Quebec (Pilon et al.
1983); 2.7-4.1 eggs, with a mode of 4, in British Columbia (van der Veen 1973); an
average of 3.12 eggs over four years on Little Galloo Island, Lake Ontario (Weseloh and
Ewins 1994); and 4.1-4.2 eggs at Columbia River Estuary colonies in Oregon (Roby et al.
1998, Collis et al. 2000).
Hatching Success
Van der Veen (1973) found that hatching success varied from 50-75 percent in DCCOs in
British Columbia. Drent et al. (1964) reported an average hatching success of 60.4
percent on Mandarte Island in British Columbia, while Mitchell (1977) observed a
hatching success of 54.2 percent in Utah. During two years of study on the Madeleine
Islands, Quebec, hatching success rates of 74.5 and 71.8 percent were observed by Pilon
et al. (1983). Roby et al. (1998) estimated hatching success in the Columbia River
Estuary to be 56 percent. Wires et al. (2001) reported that DCCO hatching success is
usually 50-75 percent.
Fledging Success
Van der Veen (1973) estimated fledging success at 74-95 percent (1.2-2.4 young per
nest). Drent et al. (1964) observed a 95 percent fledging success rate on Mandarte Island,
British Columbia, or an average of 2.4 young fledged per nest. In Utah, Mitchell (1977)
29 – Ch apter 3
reported a 72 percent fledging success rate. Pilon et al. (1983) reported fledging success
rates of 2.1 and 2.4 young per year in Québec. Slightly lower average rates of 1.8 young
fledged per nest (Hobson et al. 1989) and 1.9 young fledged per nest (Vermeer 1969)
were observed in Manitoba and Alberta, respectively. Average productivity for the Great
Lakes, between 1979 and 1991, ranged from 1.5 to 2.4 young per nest (Weseloh et al.
1995). Roby et al. (1998) and Collis et al. (2000) estimated that cormorants in the
Columbia River Estuary fledged an average of 1.6 and 1.2 chicks on East Sand Island and
2.1 and 1.6 chicks on channel markers in the estuary during 1997 and 1998, respectively.
Fowle et al. (1999) estimated productivity to be 2.5 young fledged per nest on Young
Island in Lake Champlain, Vermont. Wires et al. (2001) reported that fledging success
for DCCOs is typically 1.2-2.4 young per nest.
Survivorship
Average lifetime production has been estimated at 3.28 young per female (van der Veen
1973). Mean adult life expectancy was approximated at 6.1 years, with an estimated
first-year survival rate of 48 percent, second-year survival rate of 74 percent, and 3+
years survival rate of 85 percent (van der Veen 1973). Madenjian and Gabrey (1995)
estimated DCCO survival rates at: 58 percent from age 0 to age1; 75 percent from age 1
to 2 and age 2 to 3; and 80 percent for ages 3 to 4 and beyond. This is similar to survival
rates estimated in European Great Cormorants: 35-54 percent in the first year, 75 percent
in the second year, and 85 percent for year three and beyond (Veldkamp 1997,
Bregnballe et al. 1997). Blackwell et al. (2002) estimated that annual survival of Lake
Ontario DCCOs from fledging to just before age 1 was 30-35 percent and annual adult
survival was 85 percent. Mean annual productivity for Lake Ontario DCCOs was
estimated at 1.7-2.5 young per nest (Blackwell et al. 2002).
A major mortality factor throughout the species��� range is predation. Johnsgard (1993)
cited several studies indicating the following species as predators of DCCO chicks and/or
eggs: California Gulls, Ring-billed Gulls, Herring Gulls, Great black-backed Gulls,
American Crows, Fish Crows, Northwestern Crows, Common Ravens, and Bald Eagles.
The British Columbia Wildlife Branch has associated DCCO colony failures with
disturbance by Bald Eagles and predation by Northwestern Crows and Glaucous-winged
Gulls (1999 unpubl. data).
Other causes of mortality include disease (e.g., Newcastle disease which killed over
20,000 DCCOs in colonies in the Great Lakes, Minnesota, and North and South Dakota
in 1992 [Glaser et al. 1999]), illegal human persecution, and entanglement in fishing gear
(Hatch and Weseloh 1999). Cormorant populations are influenced by both density-dependent
and density-independent factors (Cairns 1992a), with age of first breeding,
occurrence of non-breeding, and clutch abandonment the demographic parameters most
likely to respond to density (Hatch and Weseloh 1999). In a population model developed
for great cormorants in Europe, Bregnballe et al. (1997) assumed three types of density
dependent mechanisms: increased exclusion of potential breeders, reduced fledgling
production, and increased food competition on wintering grounds.
30 – Ch apter 3
Cormorants, like other fish-eating birds, accumulate contaminants from the fish they eat.
DCCO populations declined dramatically in association with high levels of contaminants
during the 1960s and early 1970s. In fact, eggs of Herring Gulls, DCCOs, and Common
Terns were found to contain some of the highest levels of organochlorine compounds in
the world (Struger et al. 1985). Effects of chlorinated hydrocarbons on DCCOs have
been most studied in the Great Lakes, where breeding populations had accumulated high
contaminant burdens and showed severe impacts (Ryckman et al. 1998, Hatch and
Weseloh 1999). Avian eggs and carcasses in Wisconsin were examined and contained
detectable levels of several organochlorine contaminants (Dale and Stromborg 1993).
The effects of these contaminants on DCCOs includes eggshell thinning (Anderson and
Hickey 1972, Postupalsky 1978), elevated embryonic mortality (Gilbertson et al. 1991),
reproductive failure and population declines (Weseloh et al. 1983, 1995), increased adult
mortality (Greichus and Hannon 1973), increased embryonic abnormalities and crossed
bills (Fox et al. 1991, Yamashita et al. 1993, Ludwig et al. 1996), egg mortality (Tillitt et
al. 1992), and brain asymmetry (Henschel et al. 1997).
Over the years, the Service and the Canadian Wildlife Service have used fish-eating birds
such as cormorants to study the impacts of long-term exposure to persistent lipophilic
environmental contaminants within the Great Lakes ecosystem (Fox et al. 1991).
Contaminant levels started decreasing in the 1970s and have continued to do so up to the
present, with most associated biological parameters improving accordingly (Hatch and
Weseloh 1999) . For example, by 1995, most contaminant residues in DCCO eggs had
declined by 83-94 percent (Ryckman et al. 1998). However, contaminant levels in Great
Lakes DCCOs continue to be significantly higher than in most other parts of North
America (Somers et al. 1993, Sanderson et al. 1994), partly because of the long
hydrologic retention times and depth of the Great Lakes, which renders them particularly
sensitive to chemical inputs (De Vault et al. 1996).
Little work has been done on the effects or occurrence of metals in cormorants. Mercury
is most often reported, but no effects have been identified in the wild (Hatch and Weseloh
1999). Methyl mercury is highly toxic; animal studies have indicated that chronic
exposure to high mercury levels is associated with kidney damage, reproductive
problems, nervous system effects, and other health problems (Johnson et al. 1998). In
New Brunswick, total mercury concentrations in tissues of DCCOs were highest of nine
seabird species examined (Braune 1987). A study in the Carson River, Nevada, found
that DCCOs had the highest mercury concentrations of three species examined (Henny et
al. unpubl. data). Additionally, recent research on loons in New York State and New
England has shown that loons are exposed to high levels of methylmercury in these areas
(“Loons sound alarm on mercury contamination,” Natl. Geog. Today, May 16, 2003).
Because of their similar niche, it can be safely assumed that DCCOs also harbor high
mercury levels in certain areas. However, contaminants are not currently a significant
limiting factor of DCCO populations at the regional or continental scale.
Double-crested Cormorant Foraging Ecology. DCCOs are rarely seen out of sight of
land and are opportunistic, generalist feeders, preying mainly upon abundant fish species
that are easy to catch (usually slow-moving or schooling fish, ranging in size from 3-40
31 – Ch apter 3
cm [1.2-16 in]), although most commonly less than 15 cm (6 in). Glahn et al. (1998)
reported that availability (i.e., abundance), rather than size, is probably the most
important factor in prey selection, but given equal availability DCCOs prefer prey fish
that are greater than 7.5 cm (3 in) in length. They also suggested that prey fish
accessibility is important in DCCO prey selection. Neuman et al. (1997) attributed
variation in DCCO diet in Lakes Huron, Erie, and Ontario to movements of fish into
shallow spawning areas and to spatial heterogeneity of fish habitat.
Studies indicate that DCCOs have strong habitat preferences with respect to depth,
distance from the breeding colony, and distance from nearest shore (Stapanian and Bur
2002). The prey of Atlantic birds suggests that they feed at the bottom of the water
column, while that of Pacific and inland birds suggests that they feed in mid-water.
DCCOs usually forage in shallow, open water (less than 8m) within 5 km of shore (Hatch
and Weseloh 1999), although they will go farther. In freshwater lakes, DCCOs forage at
fairly shallow depths and likely take prey from all levels fairly uniformly (Johnsgard
1993). A study examining DCCOs in the western basin of Lake Erie found that the most
significant foraging pressure occurred in areas within a 20 km radius of nesting colonies,
within 3 km of shore, and in waters less than or equal to 10 m in depth (Stapanian et al.
2002). Neuman et al. (1997) determined that cormorant foraging distances at Little
Galloo Island (Lake Ontario) ranged from 3.7 to 20 km (with an average distance of 13
km). Custer and Bunk (1992) reported that birds from two colonies in the Wisconsin
waters of Lake Michigan foraged an average of 2-2.4 km from the colonies, with over 90
percent of flights being within 9 km of the colonies. In Texas, Campo et al. (1993) found
that the average estimated distance from the foraging area to the nearest shore ranged
from 20 to 975 meters.
DCCOs respond rapidly to high concentrations of fish and will congregate where fish are
easily caught, such as “put and take” lakes, stocking release sites, and aquaculture ponds
(Hatch and Weseloh 1999, Wires et al. 2001). The DCCO appears to be almost
completely diurnal in its feeding habits. When pursuing prey, it dives from the surface
and chases fish underwater. While bottom-feeding is usually solitary, DCCOs may form
loose foraging flocks when feeding on schooling prey. In this way, birds create a line
that moves forward as individuals at the rear fly short distances to “leapfrog” diving birds
in the front. DCCOs engaged in this behavior have been documented in Georgian Bay,
Ontario; Massachusetts; and Green Bay, Wisconsin, as have Great Cormorants in The
Netherlands (Glanville 1992, Custer and Bunck 1992, van Eerden and Voslamber 1995,
Hatch and Weseloh 1999). Observations of such behavior were also mentioned frequently
during the public scoping period. For specifics of foraging behavior at aquaculture
facilities see Appendix 3.
3.2.2 Fish
Among natural resource agencies, a survey conducted by Wires et al. (2001) indicated
that DCCO predation was perceived to be of major importance to sport and/or
commercial fish in at least three States (Arkansas, Tennessee, and Texas), and of
moderate importance in at least eight States (Alabama, Connecticut, Louisiana, Maine,
Massachusetts, New York, Rhode Island, and Virginia). The APHIS/WS MIS database
32 – Ch apter 3
reveals that, from FY 1995-2001, of the 29 States reporting losses to natural resources, 27
reported losses to wild fish species. During public scoping, letters received from the
following States indicated concern about impacts to sport fisheries: Arkansas, Georgia,
Illinois, Kansas, Kentucky, Louisiana, Maine, Michigan, Nebraska, New York, North
Dakota, Ohio, Oklahoma, Oregon, Texas, Vermont, Wisconsin, and Wyoming.
The diet of DCCOs consists largely of fish (generally slow-moving or schooling species),
with some occurrence of aquatic animals such as insects, crustaceans, reptiles, and
amphibians (Johnsgard 1993, Hatch and Weseloh 1999). Trapp et al. (1999) conducted a
review of diet studies carried out between 1923 and 1994 and found that of 75 fish
species detected as DCCO prey items, only 29 species comprised more than 10 percent of
the diet at a specific site and, of those 29, five species consistently comprised greater than
10 percent of the diet: alewife, brook stickleback, ninespine stickleback, yellow perch,
and slimy sculpin. These results confirm the popular notion that the DCCO is an
opportunistic feeder, utilizing a wide diversity of prey. A review of the diet literature by
Wires et al. (2001) indicated that, in general, sport and commercial fish species do not
contribute substantially to DCCO diet, although they and Trapp et al. (1999) both cited
exceptions to this rule.
In general, DCCO diet varies highly among locations and tends to reflect the fish species
composition for each location, making it necessary to examine diet on a site-specific
basis (Belyea et al. 1999, Wires et al. 2001). But some regional generalizations can be
made about fish consumed by DCCOs. On the Pacific coast, no single species emerged
as the most important prey item in past studies, although some species were very
important in certain regions. In the Columbia River Estuary, diet composition differed at
the two main colonies. At Rice Island, salmonids were the most important prey item with
stickleback and peamouth also being important; at East Sand Island, shad, herring, and
sardine were the most important prey items, with salmonids and starry flounder also
important (Collis et al. 2000). In other areas, fish such as shiner perch, sculpin, gunnel,
snake prickleback, sucker, and sand lance proved important components of DCCO diet
(Wires et al. 2001). Aside from Pacific salmonids, several of which are Federally-listed
as threatened or endangered, the populations of none of these fish species are a regional
or national concern.
In the Great Lakes, fish species such as alewife and gizzard shad, appear to be the most
important prey items. Stickleback, sculpin, cyprinids, and yellow perch and, at some
localities, burbot, freshwater drum, and lake/northern chub are also important prey fish
species (Wires et al. 2001). Stapanian et al. (2002) wrote that, “Diet and foraging studies
in the Great Lakes suggest that cormorants are opportunistic foragers that eat mostly
small prey fish, such as young-of-the-year and yearling gizzard shad…, emerald
shiner…, freshwater drum…, alewives…, and sticklebacks…,” most of which have little
sport or commercial value, while noting that “cormorants consume large quantities of
smallmouth bass and yellow perch in the waters near Little Galloo Island in Lake
Ontario.” Studies suggest that considerable temporal variation exists in the diet of Great
Lakes DCCOs (Johnson et al. 2002, Neuman et al. 1997); this can likely be attributed to
fish movement, much of which is related to spawning (Johnson et al. 2002).
33 – Ch apter 3
In the southeastern U.S., most of the diet consists of shad, catfish, and sunfish species
(Wires et al. 2001). In the Atlantic region, diet varies to a great extent, with no single
species emerging as most important. In coastal habitats, cod, sculpin, cunner, and gunnel
are important as well as sand lance and capelin. Where DCCOs are found inland or at
estuaries, alewife, rainbow smelt, stickleback, smallmouth bass, yellow perch,
pumpkinseed, cyprinids, and salmonids (mainly Atlantic salmon) are important prey
items (Wires et al. 2001). Of these species, Atlantic salmon are Federally-listed as
threatened, smallmouth bass and yellow perch are important sport fish, and cod, alewife,
and rainbow smelt are commercially fished. Concern about impacts of DCCO predation
on these fish has been expressed.
34 – Ch apter 3
Table 8. Geographic Range of Common DCCO Prey Species
Largemouth Bass: originally ranged in the Atlantic slope watersheds south of Maryland, the St. Lawrence River
basin, Great Lakes, and Mississippi River basin to northeastern Mexico. They have been stocked throughout the
United States.
Smallmouth Bass: originally ranged from Minnesota to Quebec, including the Great Lakes, southward to northern
Alabama, and west to eastern Kansas and Oklahoma. Because of its sporting qualities, it has been introduced to
many other states, Canadian provinces, and 41 other countries.
Channel Catfish: naturally occurred in the central and eastern United States and southern Canada. They ranged
throughout the Mississippi River drainage to northeast Mexico; to the east from the St. Lawrence River, along the
western slope of the Appalachian Mountains to central Florida. They were conspicuously absent along the
watersheds of the Atlantic seaboard. The species has been widely introduced for sport fishing throughout the
United States.
Walleye: native range is throughout most of eastern North America, including Great Lakes, but has been
introduced to Western North American streams where habitat is suitable.
Northern Pike: range is extensive, greater than any other freshwater game fish. Pike can be found throughout the
northern half of North America, including the Great Lakes.
Yellow Perch: on the Atlantic coast, range from South Carolina north to Nova Scotia. They can also be found west
through the southern Hudson Bay region to Saskatchewan, including the Great Lakes, and south to the northern
half of the Mississippi drainage.
Bluegill: original range includes most of central and eastern United States, north into southern Canada.
Alewife: native to the Atlantic Coast and entered the upper Great Lakes through the Welland Canal. Alewife
populations have become established in Great Lakes and many landlocked lakes in New York, Maine,
Connecticut, and other New England states.
Gizzard Shad: Mississippi and Atlantic drainages, including the Great Lakes.
Rainbow Smelt: essentially a marine species with chief distribution along Canadian coastal waters. Intruded into
fresh waters of northeastern U.S. and the Great Lakes.
Health of the Great Lakes: An Overview. In order to examine the cormorant population
explosion in the U.S. and Canadian Great Lakes and its impact to fisheries from an
“ecological” perspective, it helps to examine the ecosystem health of the Great Lakes.
An excellent overview of the aquatic community health of the Great Lakes is that of a
working paper presented at the State of the Lake Ecosystem Conference (Koonce 1995).
This discussion is derived largely from that source. By most standards, the Great Lakes
ecosystems are “extremely unhealthy.” The most notable justifications for this
description are the Lakes’ dramatic loss of biological diversity and the establishment of
non-indigenous populations (Koonce 1995).
The Great Lakes Fact Sheet produced by Environment Canada’s Ontario Region
(available online at http://www.on.ec.gc.ca/wildlife/factsheets/fs_cormorants-e.html)
provides a concise summary of the “rise and fall of Great Lakes fish populations”:
Great Lakes fish populations have undergone some profound changes in the last 60 years. One of these was
the dramatic decline of large predatory fish, primarily Lake Trout and, to a lesser extent, Burbot. In Lake
Ontario the most dramatic declines of these species occurred in the late 1930s and 1940s, while in Lake
Huron they occurred during the 1940s and 1950s. The decline of the predatory fish was caused by many
factors, including years of heavy fishing, the invasion of the sea lamprey, the loss of spawning areas.
Increased amounts of toxic contaminants entering the lakes may have also been a factor.
With the decline of larger predatory fish, the smaller fish species underwent an unprecedented population
explosion. The main species involved in this increase were Rainbow Smelt and Alewife, neither of which
was native to the upper Great Lakes. Rainbow Smelt were introduced to the Great Lakes in Michigan in
1912. They spread slowly through the lakes, becoming common in Lakes Michigan and Huron by the
35 – Ch apter 3
1930s and in Lakes Ontario and Erie by the late 1940s. Alewife were abundant in Lake Ontario by the
1890s but did not become common in Lakes Michigan and Huron until the demise of the Lake Trout in the
mid-late 1940s.
Thus, for a period of 30 years (1950s - 1970s) these smaller prey species increased in a manner more or less
unchecked by any predatory fish or birds higher up the food web. The smaller prey fish came under heavy
predation pressure in the 1980s, with the massive stocking of salmon and trout in most of the Great Lakes.
As a result, the population of smaller fish decreased. However, in spite of this predation, Alewife remained
abundant throughout much of the Great Lakes and were fed upon heavily by cormorants during this period.
Indeed, fish play a major role in structuring aquatic ecosystems. At least 18 fish species
of historical importance have declined significantly or disappeared from one or more of
the Great Lakes (Koonce 1995). Accompanying these changes in native biodiversity
have been a series of invasions and introductions of non-native fish species. Species that
have established substantial populations include: sea lamprey, alewife, rainbow smelt,
gizzard shad, white perch, carp, brown trout, Chinook salmon, coho salmon, pink salmon,
rainbow trout, ruffe, rudd, fourspine stickleback, and two species of goby. In total, 139
non-native aquatic organisms (including plants, invertebrates, and fish) have become
established in Great Lakes ecosystems (Koonce 1995).
These changes in the biodiversity of the Great Lakes have been, and continue to be,
caused by a number of chemical, physical, and biological stresses, the most important of
which include: (1) large-scale degradation of tributary and nearshore habitat for fish and
wildlife; (2) imbalances in aquatic communities due to population explosions of invading
species such as sea lamprey, alewife, white perch, and zebra and quagga mussels; (3)
reproductive failure of lake trout; (4) alterations of fish communities and loss of
biodiversity associated with overfishing and fish stocking practices; and (5) impacts of
persistent toxic chemicals on fish and wildlife (Koonce 1995).
Koonce (1995) also noted that “evaluation of the health of the aquatic community of the
Great Lakes is complicated,” mainly due to three important factors. First, identification
of factors responsible for particular population effects (e.g., increased mortality rates or
decreased reproductive rates) is difficult because different factors can produce similar
effects on populations. Second, since populations and communities are adaptive, with
healthy communities able to self-regulate in the presence of internal/external stresses, a
variety of “healthy” states may be functionally equivalent (in at least an ecological
sense). Third, the Great Lakes are disturbed ecosystems for which there are no
undisturbed communities to serve as benchmarks for recovery; thus, “the determination
of the wellness of an ecosystem requires a value judgment.”
3.2.3 Other Birds
In a survey conducted by Wires et al. (2001), impacts to other bird species were reported
by the States of Arkansas, Illinois, Iowa, Maine, Massachusetts, Michigan, Mississippi,
New York, Ohio, Vermont, and Wisconsin. Impacts to other colonial waterbirds,
particularly herons and egrets, were reported most often and these impacts were
associated mainly with habitat degradation and competition for nest sites. During our
EIS public comment periods, several resource agencies expressed concern about actual or
potential impacts to other birds.
36 – Ch apter 3
Over the course of their life cycle, individual DCCOs may interact with other species of
birds in a variety of ways. These interactions may involve competition for nest sites,
competition for food, and disease transmission.
37 – Ch apter 3
Table 9. Avian Associates of DCCOs (Source: Kaufman 1996 and Ehrlich et al. 1988)
American White Pelican: Habitat includes lakes, marshes, salt bays. Total population probably declined through
first half of 20th century, but has increased substantially since 1970s.
Anhinga: Habitat includes cypress swamps, rivers, and wooded ponds in the southern U.S.
Black-crowned Night-Heron: Habitat includes marshes and shores; roosts in trees. Populations probably declined
in 20th century due mostly to habitat loss; in recent years, overall population is generally stable or increasing, but
declining in the U.S. Great Lakes. See Table 10 below.
Brandt’s Cormorant: Habitat includes rocky areas along Pacific coast. Local populations fluctuate, but overall
numbers probably stable.
Caspian Tern: Habitat includes large lakes, coastal waters, beaches, bays. Overall population probably stable,
perhaps increasing.
Common Tern: Habitat includes lakes, ocean, bays, beaches. Northeastern populations probably lower than they
were historically. Some inland populations declining, including Great Lakes.
Great Black-backed Gull: Habitat mostly includes coastal waters and estuaries along the Atlantic coast. Populations
increasing and breeding range steadily expanding.
Great Blue Heron: Habitat includes marshes, swamps, shores, tideflats; very adaptable. Common and widespread,
numbers stable or increasing.
Great Cormorant: Habitat includes ocean cliffs with some found on large inland rivers in winter. North American
population (also found throughout Europe) has increased dramatically in recent decades, and breeding range has
expanded southward along Atlantic coast.
Great Egret: Habitat includes marshes, ponds, shores, mudflats. Nearly decimated by plume hunters in 19th century,
recovered in 20th century. In recent decades, breeding range has gradually expanded northward, with some
evidence that southern populations have declined.
Herring Gull: Habitat includes ocean coasts, bays, beaches, lakes, piers, farmlands, dumps. Populations increased
greatly in 20th century and breeding range expanded.
Neotropic Cormorant: Habitat includes tidal waters and lakes in the southern U.S. After declines in Texas numbers
in the 1950s and 1960s, is increasing again and may be spreading north inland.
Pelagic Cormorant: Habitat includes cliffs and other rocky areas along Pacific coast. Population probably stable,
with close to 75% occurring in Alaska.
Ring-billed Gull: Habitat includes lakes, bays, coasts, piers, dumps, plowed fields. Populations high and probably
still increasing.
Snowy Egret: Habitat includes marshes, swamps, ponds, shores. Nearly decimated by plume hunters in 19th
century, recovered in 20th century. Has expanded breeding range northward in recent decades; populations
increasing.
Western Gull: Habitat includes coastal waters, estuaries, beaches, offshore islands, city waterfronts. Common, with
overall numbers stable.
38 – Ch apter 3
Table 10. Comparisons of population estimates of Black-crowned Night-Herons in the
Great Lakes in 1976–80, 1989–91, and 1997–2000 (from Blokpoel and Tessier 1998;
Cuthbert et al. 2002; C. Weseloh unpubl. data; L. Harper unpubl. data)
Body of
Water
1976–1980 1989–1991 1997–2000
No. of
breeding
pairs
No. of
colonies
No. of
breeding
pairs
No. of
colonies
No. of
breeding
pairs
No. of
colonies
Lake
Michigan
558 11 859 10 927 11
Lake Huron 491 12 562 13 810 19
Lake St.
Clair
0 0 98 2 0 0
Lake Erie 4,220 2 1,719 5 529 3
Niagara
River
65 1 213 2 185 3
Lake Ontario 362 6 1,221 12 1,514 10
TOTAL 5,696 32 4,672 44 3,965 46
3.2.4 Vegetation
Concern about negative impacts of nesting and roosting DCCOs to vegetation has been
expressed by the public as well as natural resource professionals. In a survey conducted
by Wires et al. (2001) respondents from Alabama, Arkansas, Connecticut, Florida, Iowa,
Maine, Maryland, Michigan, New Hampshire, New York, North Carolina, Ohio,
Oklahoma, Rhode Island, Vermont, and Wisconsin reported impacts to trees, while the
States of Iowa, Maine, Maryland, Michigan, New Hampshire, Ohio, Oklahoma, Vermont,
Virginia, and Wisconsin reported impacts to herbaceous layers.
DCCOs seem to prefer nesting in trees to nesting on the ground, and trees are probably
used by older, more experienced, earlier-breeding individuals (Weseloh and Ewins 1994).
Along the Pacific coast, however, DCCOs nest primarily on the ground, either in low
vegetation or on the barren ground of offshore islands and coastal cliffs. Typically,
islands with avian breeding colonies have less vegetative cover than adjacent islands with
none and, in general, plant species diversity tends to be low in colonial waterbird nesting
colonies (Chapdelaine and Bédard 1995). The chief concerns associated with DCCO-induced
vegetation damage are displacement of other colonial waterbird species (caused
by habitat changes) and harm to plant species/communities of special management
significance. Into the latter category falls the Carolinian forest vegetation type, the
northernmost geographic extension of the eastern deciduous forest ecosystem. In
Canada, even though the Carolinian vegetation zone makes up only 1 percent of Canada's
total land area, it boasts a greater number of species of flora and fauna, many of which
are considered rare, than any other ecosystem in Canada
(http://www.carolinian.org/Cc1.htm).
3.2.5 Federally-listed Species
A concern among members of the public and wildlife professionals, including Service
and Wildlife Services personnel, is the impact of damage management methods and
activities on non-target species, particularly Threatened and Endangered species.
39 – Ch apter 3
Another concern is potential impacts to Threatened and Endangered species caused by
DCCOs themselves. For example, during the public scoping period, the Maine
Department of Inland Fisheries and Wildlife listed DCCO predation on stocked and
native Atlantic salmon as an issue of concern. Additionally, during the DEIS comment
period, the State of Washington stated their concern about impacts of DCCO predation on
wild salmonids.
Section 7 of the Endangered Species Act (ESA), as amended (16 U.S.C. 1531-1543; 87
Stat. 884), provides that, “The Secretary shall review other programs administered by
him and utilize such programs in furtherance of the purposes of this Act'' (and) shall
“ensure that any action authorized, funded or carried out ... is not likely to jeopardize the
continued existence of any endangered species or threatened species or result in the
destruction or adverse modification of (critical) habitat ...'' Consequently, we completed
an intra-Service biological evaluation and informal Section 7 consultation under the ESA
for the proposed action.
3.3 Socioeconomic Environment
Concerns about increasing DCCO populations extend beyond the biological to include
social and economic impacts as well.
3.3.1 Water Quality and Human Health
The major human health concern expressed during public scoping was contamination of
water supplies by DCCO excrement. Eight States expressed concern over possible
DCCO-related impacts to water quality in a survey conducted by Wires et al. (2001).
Those States were Alabama, Arkansas, Connecticut, Maine, Massachusetts, Michigan,
Rhode Island, and South Carolina. Additionally, residents of Henderson, New York, near
Little Galloo Island in eastern Lake Ontario (home to a very large DCCO colony),
expressed concern about DCCOs presenting a threat to their groundwater.
Waterbird excrement can contain coliform bacteria, streptococcus bacteria, Salmonella,
toxic chemicals, and nutrients, and it is known to compromise water quality, depending
on the number of birds, the amount of excrement, and the size of the water body.
Although the 1992 Section 305(b) State Water Quality Reports indicate that, overall, the
Nation's groundwater quality is good to excellent, many local areas have experienced
significant groundwater contamination. The sources and types of groundwater
contamination vary depending upon the region of the country, but those most frequently
reported by States include: leaking underground storage tanks, septic tanks, municipal
landfills, agricultural activities, and abandoned hazardous waste sites (EPA 1992).
Concerns about water quality and DCCOs exist on two levels: contaminants and
pathogens.
Contaminants. Elevated contaminant levels associated with breeding and/or roosting
concentrations of DCCOs and their potential effects on groundwater supplies are the
major concerns regarding DCCO impacts to human health. Metals and toxic organic
chemicals typically originate in industrial discharges, runoff from city streets, mining
activities, leachate from landfills, and a variety of other sources. These toxic chemicals,
40 – Ch apter 3
which are generally persistent in the environment, can cause death or reproductive failure
in fish, shellfish, and wildlife. In addition, they can accumulate in animal tissue, be
absorbed in sediments, or find their way into drinking water supplies, posing long-term
health risks to humans (EPA 1992).
The most toxic and persistent environmental contaminants include chlorinated
hydrocarbons (also known as organochlorine chemicals; e.g., PCBs, dioxin-like
compounds, and certain pesticides such as DDT). These compounds are lipophilic
(meaning they become chemically bound to fat molecules) and accumulate in individual
organisms via a process known as bioaccumulation. Then, as a result of
biomagnification, these chemicals, bound in organisms, occur at greater concentrations
with each step of the food chain. Thus, species at the top of the food chain, such as
DCCOs, harbor the greatest, and most toxic, levels of these contaminants.
Pathogens. Escherichia coli (E. coli) are fecal coliform bacteria associated with fecal
material of warm blooded animals. There are over 200 specific serological types of E.
coli and the majority are harmless (Sterritt and Lester 1988). Aquatic birds can be a
source of fecal contamination of water resources. For example, Simmons et al. (1995)
used genetic fingerprinting to link fecal contamination of small ponds on Fisherman
Island, Virginia to waterfowl. Klett et al. (1998) were able to implicate waterfowl and
gulls as the source of fecal coliform bacteria at the Kensico Watershed, a water supply for
New York City. Also, fecal coliform bacteria counts correlated with the number of
Canada Geese and gulls roosting at the reservoir (Klett et al. 1998). Additionally,
excessive numbers of resident Canada Geese can affect water quality around beaches and
in wetland

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U.S. Fish and Wildlife Service
Final Environmental Impact Statement
Double-crested Cormorant Management in the United
States
U.S. Department of Interior Fish and Wildlife Service
“Working with others to conserve, protect, and enhance fish, wildlife, and
plants and their habitats for the continuing benefit of the American people”
in cooperation with
U.S. Department of Agriculture APHIS Wildlife Services
“Providing leadership in wildlife damage management in the protection of
America’s agricultural, industrial and natural resources, and safeguarding public
health and safety”
2003
i
FINAL ENVIRONMENTAL IMPACT STATEMENT:
Double-crested Cormorant Management
RESPONSIBLE AGENCY: Department of the Interior
U.S. Fish and Wildlife Service
COOPERATING AGENCY: Department of Agriculture
Animal and Plant Health Inspection Service
Wildlife Services
RESPONSIBLE OFFICIAL: Steve Williams, Director
U.S. Fish and Wildlife Service
Main Interior Building
1849 C Street
Washington, D.C. 20240
FOR FURTHER INFORMATION
CONTACT: Shauna Hanisch, EIS Project Manager
Division of Migratory Bird Management
U.S. Fish and Wildlife Service
4401 N. Fairfax Drive MS-MBSP-4107
Arlington, Virginia 22203
(703) 358-1714
Brian Millsap, Chief
Division of Migratory Bird Management
U.S. Fish and Wildlife Service
4401 N. Fairfax Drive MS-MBSP-4107
Arlington, Virginia 22203
(703) 358-1714
ii
SUMMARY
Populations of Double-crested Cormorants have been increasing rapidly in many parts of
the U.S. since the mid-1970s. This abundance has led to increased conflicts, both real
and perceived, with various biological and socioeconomic resources, including
recreational fisheries, other birds, vegetation, and hatchery and commercial aquaculture
production. This document describes and evaluates six alternatives (including the
proposed action) for the purposes of reducing conflicts associated with cormorants,
enhancing the flexibility of natural resource agencies to deal with cormorant conflicts,
and ensuring the long-term conservation of cormorant populations. There are four
chapters that make up the critical components of an Environmental Impact Statement.
Chapter 1, Purpose and Need, describes the purpose of and need for the action. Chapter
2, Alternatives, describes the six management alternatives that we considered: (1)
Continue current cormorant management practices (No Action); (2) implement only non-lethal
management techniques; (3) expand current cormorant damage management
practices; (4) establish a new depredation order to address public resource conflicts
(PROPOSED ACTION); (5) reduce regional cormorant populations; and (6) establish
frameworks for a cormorant hunting season. Chapter 3, Affected Environment, introduces
the reader to the environmental categories upon which the analysis of alternatives in
chapter 4 is based: cormorant populations, fish, other birds, vegetation, Federally-listed
Threatened and Endangered species, water quality and human health, economic impacts,
fish hatcheries and environmental justice, property losses, and existence and aesthetic
values. Chapter 4, Environmental Consequences, analyzes the predicted impacts of each
alternative on the environmental categories outlined in chapter 3 and in comparison to the
No Action alternative. The environmental analysis presented in Chapter 4 indicates that
the PROPOSED ACTION: will cause the estimated take of <160,000 DCCOs, which is
not predicted to have a significant negative impact on regional or continental DCCO
populations; will cause localized disturbances to other birds but these can be minimized
by taking preventive measures, leading to the action having beneficial effects overall;
will help reduce localized fishery and vegetation impacts; will not adversely affect any
Federally-listed species; is likely to help reduce localized water quality impacts; will help
reduce depredation of aquaculture and hatchery stock; is not likely to significantly benefit
recreational fishing economies or commercial fishing; may indirectly reduce property
damages; and will have variable effects on existence and aesthetic values, depending on
perspective.
iii
TABLE OF CONTENTS
CHAPTER 1: PURPOSE OF AND NEED FOR ACTION.............................................................1
1.1 Introduction...................................................................................................................1
1.2 Purpose of Action..........................................................................................................2
1.3 Need for Action.............................................................................................................2
1.3.1 Biological...................................................................................................2
1.3.2 Socioeconomic...........................................................................................3
1.4 Background Information...............................................................................................3
1.4.1 Lead and Cooperating Agencies................................................................3
1.4.2 Policy, Authority, and Legal Compliance.................................................3
1.4.3 Other Considerations.................................................................................6
1.4.4 Cormorant Management Practices............................................................8
1.4.5 The Role of Other Agencies in Cormorant Management.......................11
CHAPTER 2: ALTERNATIVES...................................................................................................13
2.1 Introduction..................................................................................................................13
2.2 Rationale for Alternative Design.................................................................................13
2.3 Proposed Action...........................................................................................................13
2.4 Description of Alternatives..........................................................................................13
2.4.1 Alternative A: No Action.............................................................................13
2.4.2 Alternative B: Non-lethal Management.......................................................15
2.4.3 Alternative C: Increased Local Damage Control.........................................16
2.4.4 Alternative D: Public Resource Depredation Order (PROPOSED ACTION)
..............................................................................................................................17
2.4.5 Alternative E: Regional Population Reduction...........................................18
2.4.6 Alternative F: Regulated Hunting...............................................................19
2.5 Alternatives Considered but Eliminated from Detailed Study....................................19
2.5.1 No Management..........................................................................................19
2.5.2 Rescindment of MBTA Protection..............................................................19
2.6 Comparison of Alternatives.........................................................................................19
CHAPTER 3: AFFECTED ENVIRONMENT...............................................................................22
3.1 Introduction..................................................................................................................22
3.2 Biological Environment...............................................................................................22
3.2.1 Double-crested Cormorants.........................................................................22
3.2.2 Fish...............................................................................................................31
3.2.3 Other Birds...................................................................................................35
3.2.4 Vegetation....................................................................................................38
3.2.5 Federally-listed Species...............................................................................38
3.3 Socioeconomic Environment.......................................................................................39
3.3.1 Water Quality and Human Health...............................................................39
3.3.2 Economic Environment...............................................................................40
3.3.3 Fish Hatcheries and Environmental Justice................................................45
3.3.4 Property Losses...........................................................................................46
3.3.5 Existence and Aesthetic Values..................................................................46
3.3.6 Issues Raised but Eliminated from Detailed Study....................................47
CHAPTER 4: ENVIRONMENTAL CONSEQUENCES.............................................................51
4.1 Introduction.................................................................................................................51
iv
4.2 Environmental Analysis of Alternatives....................................................................52
4.2.1 Impacts to Double-crested Cormorants.......................................................52
4.2.2 Impacts to Fish............................................................................................59
4.2.3 Impacts to Other Birds................................................................................66
4.2.4 Impacts to Vegetation.................................................................................75
4.2.5 Impacts to Federally-listed Species...........................................................78
4.2.6 Impacts to Water Quality and Human Health............................................80
4.2.7 Economic Environment..............................................................................82
4.2.8 Impacts to Hatcheries and Environmental Justice......................................92
4.2.9 Impacts to Property Losses..........................................................................95
4.2.10 Impacts to Existence and Aesthetic Values..............................................96
4.3 Further Discussion of Alternatives..............................................................................98
4.3.1 Alternative A: No Action............................................................................98
4.3.2 Alternative B: Non-lethal Management....................................................100
4.3.3 Alternative C: Increased Local Damage Control......................................101
4.3.4 Alternative D: Public Resource Depredation Order (PROPOSED ACTION)
............................................................................................................................103
4.3.5 Alternative E: Regional Population Reduction.........................................105
4.3.6 Alternative F: Regulated Hunting.............................................................106
4.3.7 Mitigating Measures.................................................................................107
CHAPTER 5: LIST OF PREPARERS.........................................................................................114
CHAPTER 6: CONSULTATION AND COORDINATION AGENCIES..................................116
6.1 Introduction...............................................................................................................116
6.2 Issues of Concern and Management Options Identified During Scoping................116
6.3 Public Comments Expressed During the DEIS Comment Period............................117
6.4 List of Agencies, Organizations, and Individuals.....................................................119
CHAPTER 7: PUBLIC COMMENT ON DEIS AND RESPONSE...........................................121
CHAPTER 8: REFERENCES CITED........................................................................................139
APPENDICES
Appendix 1: List of Scientific Names
Appendix 2: Distribution of DCCO Breeding Colonies in North America
Appendix 3: DCCO Foraging Behavior at Aquaculture Facilities
Appendix 4: DCCO Management Techniques
Appendix 5: Methodology for Estimating Take under the Aquaculture Depredation Order
Appendix 6: Discussion of Fishery Impacts
Appendix 7: Guidelines for Distinguishing DCCOs from Anhingas and Neotropic Cormorants
Appendix 8: Overview of Aquaculture Production in 13 States
Appendix 9: Costs of Control Methods and Techniques
Appendix 10: Comparison Tables Using Christmas Bird Count Data
Appendix 11: Public Scoping Report
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CHAPTER 1: PURPOSE OF AND NEED FOR ACTION
1.1 Introduction
The persistence of conflicts associated with Double-crested Cormorants (hereafter,
DCCOs or cormorants; see Appendix 1 for a list of scientific names), widespread public
and agency dissatisfaction with the status quo, and the desire to develop a more
consistent and effective management strategy for DCCOs led the U.S. Fish & Wildlife
Service (Service or we) to reexamine, and if deemed necessary, to amend our policies and
practices for the management of cormorants in the contiguous United States.
We chose to prepare an Environmental Impact Statement (EIS), as suggested by National
Environmental Policy Act (NEPA) guidelines, including: (1) Council on Environmental
Quality (CEQ) regulations in 40 CFR 1508.18, which define a “major Federal action” as
“adoption of formal plans, such as official documents prepared or approved by Federal
agencies which guide or prescribe alternative uses of Federal resources, upon which
future agency actions will be based;” and (2) Service policy in section 550FW 3.3B(2)
which states that criteria triggering the preparation of an EIS include precedent-setting
actions with wide-reaching or long-term implications, changes in Service policy having a
major positive or negative environmental effect, and/or conflicts with local, regional,
State or Federal proposed or adopted plans or policies.
As stated in 40 CFR 1502.1, the purpose of an EIS is to provide a detailed explanation of
the significant environmental consequences, both good and bad, of a proposed action.
This explanation includes significant effects on the natural, economic, social, and cultural
resources of the affected environment. An EIS is to be prepared to inform decision-makers
and the public of the proposed action and its reasonable alternatives. It should
focus on significant environmental issues. This Final EIS (FEIS) identifies and provides
an evaluation of six alternative approaches for managing DCCOs, including the proposed
action (Alternative D). Each alternative is analyzed based on anticipated impacts to
various biological and socioeconomic impact areas. This FEIS is a comprehensive,
programmatic plan intended to guide and direct DCCO management activities in the 48
States (excluding Hawaii and Alaska). Where NEPA analysis is suggested or required
for site-specific control projects carried out under the guidance of this document,
analyses would “tier to” or reference the FEIS. Site-specific NEPA analysis would focus
on issues, alternatives, and environmental effects unique to the project.
Because of the important role of the Wildlife Services program of the USDA Animal and
Plant Health Inspection Service (APHIS/WS) in DCCO management and research, and
the need for interagency coordination in developing future cormorant management
strategies, this FEIS is being prepared cooperatively by the Service and APHIS/WS.
This section of the FEIS discusses the purpose of and need for the action, gives
background information on the lead and cooperating agencies and the legal and policy
context of the action, describes current DCCO management activities, and summarizes
public involvement in this issue.
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1.2 Purpose of Action
In recent years, increasing populations of DCCOs have led to growing concern from the
public and natural resource management professionals about impacts of DCCOs on
various human and natural resources. Based on internal and interagency scoping and the
direction set forth in 40 CFR 1508.18 and 550 FFW3.3B (described in further detail
below), we published a Notice of Intent in the Federal Register on November 8, 1999 (64
FR 60826) announcing that we would prepare, in cooperation with APHIS/WS, an EIS
and national management plan “to [address] impacts caused by population and range
expansion of the double-crested cormorant in the contiguous United States.”
The purpose of the proposed action is threefold: to reduce resource conflicts associated
with DCCOs in the contiguous United States, to enhance the flexibility of natural
resource agencies in dealing with DCCO-related resource conflicts, and to ensure the
long-term conservation of DCCO populations.
1.3 Need for Action
While cormorant-human conflicts are not new, from either a historical or a global
perspective (Siegel-Causey 1999; Hatch 1995, van Eerden et al. 1995, Wires et al. 2001),
the DCCO’s rapid population increase over the past 25 years has brought these conflicts
in the U.S. to the point of justifying greater management attention. There is a need for
the Service to allow others to conduct DCCO control to limit negative impacts to the
maximum extent practicable.
The issue of “need” can also be considered from the perspective of other agencies and
parties with a stake in DCCO management. APHIS/WS issued a position statement
emphasizing the need for scientifically-based DCCO population reduction in order to
reduce impacts to aquaculture producers and other resources. Of the 27 States that
commented during the public scoping period, 16 of these expressed desire for increased
management flexibility and/or greater population management of DCCOs. Many non-agency
stakeholders also stated that there is a need for increased DCCO control to reduce
resource impacts.
1.3.1 Biological
The recent increase in the North American DCCO population, and subsequent range
expansion, has been well-documented (Scharf and Shugart 1981, Milton and Austin-
Smith 1983, Buckley and Buckley 1984, Hatch 1984, Ludwig 1984, Blokpoel and
Harfenist 1986, Price and Weseloh 1986, Roney 1986, Craven and Lev 1987, Hobson et
al. 1989, Hatch 1995, Weseloh et al. 1995, Glahn et al. 1999, Tyson et al. 1999, Hatch
and Weseloh 1999, Wires et al. 2001). There is a need to reduce the biological impacts
resulting from this population increase which include: adverse effects on other bird
species through habitat destruction, exclusion, and/or nest competition; declines in fish
populations associated with DCCO predation; destruction of vegetation, particularly
where DCCOs nest; and predation on Federally-listed fish species. There is a need to
provide for localized variation in DCCO control because the occurrence and severity of
these impacts varies from region to region.
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1.3.2 Socioeconomic
Socioeconomic impacts include economic losses to aquaculture producers, commercial
fisheries, and fishing-related businesses; losses to private resources (including fish in
private lakes and damaged trees); and compromised water quality. As with biological
impacts, the occurrence and severity of these impacts varies from region to region. There
is a need to reduce these impacts.
1.4 Background Information
1.4.1 Lead and Cooperating Agencies
USDI Fish and Wildlife Service. The primary responsibility of the Service is fish,
wildlife, and plant conservation. Our mission is “working with others to conserve,
protect, and enhance fish, wildlife, and plants and their habitats for the continuing benefit
of the American people.” While some of the Service's responsibilities are shared with
other Federal, State, Tribal, and local entities, we have special authorities in managing
the National Wildlife Refuge System; conserving migratory birds, endangered species,
certain marine mammals, and nationally significant fisheries; and enforcing Federal
wildlife laws. The Division of Migratory Bird Management mission is “providing global
leadership in the conservation and management of migratory birds for present and future
generations.” One of the Service’s long-term goals, as stated in the 2000-2005 Service
Strategic Plan, is “migratory bird conservation.” The purpose of this goal is “to improve
the status of migratory bird populations that have evidenced decline or other significant
problems, including overabundance.”
USDA Animal and Plant Health Inspection Service-Wildlife Services. The Wildlife
Services program of the U.S. Department of Agriculture Animal and Plant Health
Inspection Service (APHIS/WS) is responsible for managing conflicts with and damages
caused by wildlife, including migratory birds. APHIS/WS' mission is to “provide
leadership in wildlife damage management in the protection of America's agricultural,
industrial and natural resources, and to safeguard public health and safety.” This is
accomplished through: training of wildlife damage management professionals;
development and improvement of strategies to reduce economic losses and threats to
humans from wildlife; collection, evaluation, and dissemination of management
information; cooperative wildlife damage management programs; informing and
educating the public on how to reduce wildlife damage and; providing data and a source
for limited use management materials and equipment, including pesticides (USDA-APHIS
1989).
1.4.2 Policy, Authority, and Legal Compliance
Migratory Bird Treaty Act of 1918, as amended (16 U.S.C. 703-711: 40 Stat. 755).
The Service has the primary statutory authority to manage migratory bird populations in
the United States, authority which comes from the Migratory Bird Treaty Act (MBTA).
The original treaty was signed by the U.S. and Great Britain (on behalf of Canada) in
1918 and imposed certain obligations on the U.S. for the conservation of migratory birds,
including the responsibilities to: conserve and manage migratory birds internationally;
sustain healthy migratory bird populations for consumptive and non-consumptive uses;
and restore depleted populations of migratory birds. Conventions with Mexico, Japan,
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and Russia occurred in later years. The cormorant taxonomic family, Phalacrocoracidae,
and 31 other families were added to the List of Migratory Birds (that is, those bird
species protected by the MBTA) in 1972 as a result of an amendment to the 1936
“Convention between the United States of America and the United Mexican States for the
Protection of Migratory Birds and Game Mammals” (23 U.S.T. 260, T.I.A.S. 7302).
Thus, since 1972, DCCOs have been a trust resource managed by the Service for the
American people under the authority of the MBTA.
Animal Damage Control Act of 1931 and Rural Development, Agriculture, and Related
Agencies Appropriations Act of 1988 (7 U.S.C. 426-426c; 46 Stat. 1468).
The U.S. Department of Agriculture is directed by law to protect American agriculture
and other resources from damage associated with wildlife. The primary statutory
authority for the APHIS/WS program is the Animal Damage Control Act of March 2,
1931 (7 U.S.C. 426-426c; 46 Stat. 1468), as amended in the Fiscal Year 2001 Agriculture
Appropriations Bill, which provides that:
The Secretary of Agriculture may conduct a program of wildlife services with respect to injurious animal
species and take any action the Secretary considers necessary in conducting the program. The Secretary
shall administer the program in a manner consistent with all of the wildlife services authorities in effect on
the day before the date of the enactment of the Agriculture, Rural Development, Food and Drug
Administration, and Related Agencies Appropriations Act, 2001.
Since 1931, with the changes in societal values, APHIS/WS policies and programs place
greater emphasis on the part of the Act discussing “bringing [damage] under control,”
rather than “eradication” and “suppression” of wildlife populations. In 1988, Congress
strengthened the legislative mandate of APHIS/WS with the Rural Development,
Agriculture, and Related Agencies Appropriations Act. This Act states, in part:
That hereafter, the Secretary of Agriculture is authorized, except for urban rodent control, to conduct
activities and to enter into agreements with States, local jurisdictions, individuals, and public and private
agencies, organizations, and institutions in the control of nuisance mammals and birds and those mammal
and bird species that are reservoirs for zoonotic diseases, and to deposit any money collected under any
such agreement into the appropriation accounts that incur the costs to be available immediately and to
remain available until expended for Animal Damage Control activities.
Endangered Species Act (ESA), as amended (7 U.S.C. 136; 16 U.S.C. 460 et seq.).
It is Federal policy, under the ESA, that all Federal agencies seek to conserve threatened
and endangered species and utilize their authorities in furtherance of the purposes of the
Act (Sec.2(c)). In accordance with section 7 of the Act, the Service has prepared a
Biological Evaluation and conducted informal consultation with the Service Endangered
Species Program to evaluate Federally-listed species that may be affected by the
proposed action.
National Environmental Policy Act of 1969 (NEPA), as amended (42 U.S.C. 4321-4347).
NEPA is our national charter for protection of the environment; it requires Federal
agencies to evaluate the potential environmental impacts when planning a major Federal
action and ensures that environmental information is available to public officials and
citizens before decisions are made and before actions are taken.
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In general, the NEPA process entails: determining what need must be addressed;
identifying alternative ways of meeting the need; analyzing the environmental impacts of
each alternative; and deciding which alternative to pursue and how. While NEPA does
not place environmental protection over all other public values, it does require a thorough
consideration of the environmental impacts associated with management actions. NEPA
neither requires a particular outcome nor that the “environmentally-best” alternative is
selected. It mandates a process for thoroughly considering what an action may do to the
human environment and how any adverse impacts can be mitigated
(http://npi.org/nepa/process.html).
More specifically, there are seven major steps in the planning process for the
development of an EIS and the implementation of the proposed action. These include:
1) Publication of Notice of Intent – The Notice of Intent to prepare an Environmental
Impact Statement and national cormorant management plan was published in the Federal
Register (64 FR 60826) on November 8, 1999. This initiated the scoping process.
2) Identification of Issues and Concerns – The Notice of Intent solicited public
participation in the scoping process, which is the chief way that issues, concerns, and
potential management options are communicated from the public to the lead agency. In
addition to writing or e-mailing comments, citizens could attend any of twelve public
meetings held across the country. The scoping period ended on June 30, 2000. All
comments were read, compiled, and summarized in a public scoping report.
3) Development of Alternatives – Following scoping, six alternatives were developed to
offer a range of options for managing DCCOs. These were based on NEPA regulations,
public comments, interagency meetings, internal discussion, and review of available
scientific information.
4) Analysis of Environmental Effects – After significant issues and alternatives were
established, the environmental analysis was prepared in order to help the public and
decision-makers understand the environmental consequences of the various alternatives.
5) Publication of Notice of Availability of Draft Environmental Impact Statement – The
notice of availability for the DEIS was published in the Federal Register on December 3,
2001 (66 FR 60218) and announced the completion of the DEIS and its availability for
public review. It was followed by 10 public meetings and a 100-day comment period.
6) Publication of Notice of Availability of Final Environmental Impact Statement – This
Federal Register publication follows the public comment period for the DEIS and
announces the completion of the Final EIS, followed by a 30-day waiting period.
7) Publication of Record of Decision – This is the final step of the EIS decision-making
process, which states the selected alternative and why it was chosen. The actions
associated with the EIS cannot be taken until the Record of Decision is issued.
6 – Chapter 1
Environmental Justice and Executive Order 12898. Executive Order 12898, entitled
“Federal Actions to Address Environmental Justice in Minority Populations and Low-
Income Populations,” promotes the fair treatment of people of all races, income levels
and cultures with respect to the development, implementation and enforcement of
environmental laws, regulations and policies. Environmental justice is the pursuit of
equal justice and protection under the law for all environmental statutes and regulations
without discrimination based on race, ethnicity, or socioeconomic status.
Executive Order 13186. Executive Order 13186, entitled “Responsibilities of Federal
Agencies to Protect Migratory Birds,” directs any Federal agency whose actions have a
measurable negative impact on migratory bird populations to develop a Memorandum of
Understanding (MOU) with the Service to promote conservation of migratory birds. The
MOUs would identify positive actions that Federal agencies can apply to ensure their
activities consider the conservation of migratory birds. The Executive Order (EO) also
requires the Secretary of Interior to establish a Council for the Conservation of Migratory
Birds to oversee implementation of the EO. The council will be composed of
representatives from the Departments of Interior, Commerce, Agriculture, State,
Transportation, Energy, and Defense; the Environmental Protection Agency; and other
agencies as appropriate.
1.4.3 Other Considerations
Conceptual Foundations. “Conceptual foundations” are the set of principles and
assumptions that direct management activities (Anderson 1991). They influence how we
interpret information, identify problems, and select approaches to their resolution (ISG
1999). Similarly, they are an expression of agency goals and philosophy, which guide
management decisions. The following five statements form the conceptual foundations
on which DCCO management is based:
(1) DCCOs are an international migratory bird resource and as such they have inherent
value regardless of their direct use to humans;
(2) While DCCOs have undergone recent range expansions, they are native to North
America;
(3) DCCOs are predators that, while a natural part of the ecosystem, can compete with
humans for fisheries, with consequences of varying ecological and socioeconomic
significance;
(4) DCCO populations have increased significantly in the past 25 years in North America
and this increase has led to both real and perceived resource conflicts;
(5) There are sound biological and socioeconomic rationales for developing a
comprehensive DCCO management strategy in the U.S.
Human Dimensions. Wildlife management is fundamentally a human, or social,
construct. One popular introductory wildlife ecology text noted that, “the practice of
wildlife management is rooted in the intermingling of human ethics, culture, [and]
perceptions” (Robinson and Bolen 1989). As human populations have grown and placed
greater demands on nature, and as human values toward wildlife resources have become
increasingly diverse, the need to better understand the “human dimensions” side of
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wildlife management has increased. Human dimensions entail “identifying what people
think and do regarding wildlife, understanding why, and incorporating that insight into
policy and management decision-making processes and programs” (Decker and
Lipscomb 1991). Thus, human dimensions address the social nature of today’s natural
resource problems (Manfredo et al. 1998), with particular relevance to “people-wildlife
problems” in which the behavior of wildlife creates a negative impact for some
stakeholders, or is perceived by some stakeholders as having adverse impacts (Decker
and Chase 1997). In a paper discussing the “social causes of the cormorant revival in the
Netherlands” (where Great Cormorants have become an overabundant species) the
authors (van Bommel et al. 2003) stated:
Ecological processes determine the potential cormorant population but social processes play a large role in
determining the actual cormorant population. Ecological systems function within the subjective boundaries
set by [people]… A problem situation can occur in which different parties disagree on the definition of
these boundaries (Pretty 1995, Pimbert and Pretty 1995). This is often the case in nature conservation
because ecosystems carry a high level of intrinsic uncertainty… When dealing with these uncertainties,
people will have different views and opinions on reality.
At a 1998 workshop on cormorant management in New York, participants agreed that
human dimensions are important in the DCCO issue because: (1) economics and
recreation are important factors; (2) it is an emotional issue that can cause polarization;
and (3) it accentuates the conflict between politics and science-based management. For
these reasons and others, the DCCO conflict can be viewed as a classic “people-wildlife
problem,” entailing both biological and social elements. The social element is made
prominent by the fact that, just as with other examples of abundant species management,
from white-tailed deer to Canada Geese, public perception of the proper way to deal with
the problem varies considerably. Conover (2002) wrote that the government’s role in
wildlife management is “to regulate the harvest of wildlife by people, to restrict human
behavior that would be detrimental to the wildlife resource, to conduct largescale
management activities, and to manage wildlife for the benefit of society.” Naturally, the
difficulty in doing so is because society is made up of diverse individuals who vary in
their perceptions of wildlife and how they want that resource managed. When conflicts
occur between wildlife and other resources that humans value, wildlife damage
management decisions must be made; these are difficult decisions to make because
stakeholder opinions are often highly polarized.
In regard to societal expectations in natural resource controversies, the Great Lakes
Fishery Resources Restoration Study (USFWS 1995), in a discussion on decision-making
and public expectations, stated:
When different segments of society place competing demands on nature, conflicts are inevitable and often
contentious... Agencies and publics are often prevented from realizing resource potential when special
interest groups fail to recognize public trust responsibilities…and the legitimacy and roles of other users.
The director of the Montana Department of Fish, Wildlife, and Parks, in the July/August
2002 edition of Montana Outdoors, succinctly described the unique position of public
agencies when he wrote:
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Some have accused us of [being extreme], of being far too biased on one issue or another. Usually the
charge comes from those who disagree with our position… The fact is, we’re rarely on the extreme ends of
any issue. Nor should we be. We’re a public agency representing the diverse interests of all [Americans].
Not just the ones who yell the loudest. Not just the ones with the most money and political clout. And not
just the ones who buy licenses. What that means is that we often take a moderate position on issues. If it
appears that we ever go “too far” on any issue or policy, believe me when I say that I could always find a
group of citizens angry that we didn’t go nearly far enough… No matter how hard we try, we won’t be able
to make everyone happy. There will always be committed, well-meaning people on either side of an issue
who think we either sold out and didn’t do enough—or that we went way too far.
In sum, management of abundant wildlife populations is a particularly challenging aspect
of wildlife conservation, one that demands that decision-makers consider a number of
important biological and socioeconomic factors. As a public agency, the Service
recognizes the importance of social, political, and economic factors in policy-making, but
emphasizes that the foundation of the Service’s mission is fish and wildlife biology.
Thus we are committed to pursuing biologically justified management strategies that are
based on the best available science and, additionally, on the knowledge and experience of
wildlife resource professionals. It is here where Romesburg’s (1981) advice that “science
and planning are different kinds of decision-making” is most relevant. Planning is the
domain of wildlife management and it:
exposes alternative images of a future possible world to the decision-maker’s values, or preferences, and
selects the best image…the images in planning are composed of scientific knowledge, common sense, rule-of-
thumb knowledge, and theories that are as yet untested… Although science and planning share common
tools, science and planning have different norms for certifying ideas, and hence criticism of these tools
must take into account the domain of their use.
The Service and APHIS/WS recognize both the controversial nature of DCCO
management and the range of values reflected in public and professional views about best
management actions. This FEIS reflects full consideration of the diverse views brought
forth during public scoping and the DEIS comment period and provides an analytical
foundation on which to base final management decisions.
1.4.4 Cormorant Management Practices
Depredation Permits. While the MBTA provides migratory birds with protection from
unauthorized take, it maintains a high degree of flexibility for dealing with human-bird
conflicts (Trapp et al. 1995). According to the MBTA, the “take” of DCCOs is strictly
prohibited except as allowed under the terms of a migratory bird permit or pursuant to
regulations.
Depredation permits to take DCCOs have been issued by the Service since 1986 and may
allow the take of eggs, adults and young, or active nests. Guidelines governing permit
issuance for migratory birds are authorized by the MBTA and subsequent regulations (50
CFR Parts 13 and 21). Specifically, Part 21.41 of Subpart D of these regulations outlines
procedures for issuing permits for the control of depredating birds. These regulations
state that all private individuals, organizations, and Federal and State agencies seeking to
control migratory birds must file an application for a depredation permit that contains the
following information: (1) a description of the area where depredations are occurring; (2)
the nature of the crops or other interests being injured; (3) the extent of such injury; and
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(4) the particular species of migratory birds committing the injury. Thus, Part 21.41
authorizes the take of migratory birds that are injuring “crops or other interests.” In
issuing depredation permits, the Service has historically interpreted “other interests” to
mean threatened and endangered species, property damage on private or public land, and
human health and safety, although permits have been issued to protect natural resources.
In 1990, Director’s Order No. 27 was instated which clarifies that the Service can issue
depredation permits for migratory, fish-eating birds preying on fish aquaculture and
hatchery facilities.
APHIS/WS typically responds to requests for assistance with bird depredation and
damage by collecting information on the type of resource being damaged, where the
damage is occurring, the number and species of birds responsible for the damage, the
economic losses resulting from the damage, and the control methods which have been
used in attempting to resolve the damage. Based upon these evaluations, APHIS/WS
personnel recommend an Integrated Damage Management approach for resolving bird
depredation and damage conflicts, which could include providing recommendations to
the Service for issuance of a depredation permit. While APHIS/WS provides
recommendations to the Service for the issuance of migratory bird depredation permits to
private entities in the cases of severe bird depredation and damage (Mastrangelo et al.
1997), the responsibility of issuing these permits rests solely with the Service (Trapp et
al. 1995). In most States, a permit is also needed from the State fish and wildlife agency.
APHIS/WS maintains a Management Information System (MIS) database documenting
the assistance that the agency provides in resolving wildlife damage conflicts. A review
of MIS data collected from FY 1995-2001 revealed that the agency responded to 1,916
technical assistance requests (“the provision of advice, recommendations, information, or
materials for use in managing wildlife damage problems” [USDA-APHIS 1997b]) to
reduce DCCO conflicts in 42 States, with Alabama, Arkansas, Florida, Louisiana,
Mississippi, and Texas representing 65 percent of the requests over the 7-year period.
MIS resource categories included aquaculture (commercially propagated finfish and
shellfish) with 72 percent of technical assistance requests; natural resources (habitat,
wildlife, wild fisheries) with 19 percent of requests; property (structures, boats,
automobiles, aircraft, pets, timber/trees) with 6 percent of requests; and human health and
safety (disease transmission to humans, wildlife aircraft strikes, direct personal injury)
with 3 percent of requests. Of those 1,916 requests, APHIS/WS recommended the
issuance of 533 depredation permits to the Service, of which over 95 percent were for the
protection of aquaculture and natural resources.
Depredation Order. In 1998, the Service issued a depredation order (USFWS 1998b; 50
CFR 21.47 ) authorizing commercial freshwater aquaculture producers in 13 States
(Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Minnesota, Mississippi,
North Carolina, Oklahoma, South Carolina, Tennessee, and Texas) to take DCCOs,
without a Federal permit, when found committing or about to commit depredations to
aquaculture stocks. The depredation order states that DCCOs may be taken by shooting
only during daylight hours, and only when necessary to protect freshwater commercial
10 – Chapter 1
aquaculture and State-operated hatchery stocks and that such actions must be carried out
in conjunction with a non-lethal harassment program certified by APHIS/WS officials.
Research and Population Surveys. Prior to 1950, the U.S. Biological Survey (predecessor
of the Fish and Wildlife Service) conducted extensive food habits studies on DCCOs and
other fish-eating birds across the continent, with particular emphasis on potential
economic impacts. More recently, the Service has conducted or funded several site-specific
studies of cormorant food habits in areas such as the Penobscot River and upper
Penobscot Bay, Maine; Les Cheneaux Islands, Michigan; and the Mississippi River
Delta, Mississippi. In 1999, the Service provided funding for a DCCO population status
assessment to be prepared by researchers from the University of Minnesota and utilized
in the development of this EIS (Wires et al. 2001). This report, “The Status of the
Double-Crested Cormorant (Phalacrocorax auritus) in North America,” is available
online at http://migratorybirds.fws.gov/issues/cormorant/status.pdf.
DCCO population monitoring is carried out cooperatively by the Service, APHIS/WS,
the Canadian Wildlife Service, the States, and various universities. The U.S. Geological
Survey (Patuxent Wildlife Research Center) and non-governmental organizations
participate in recording and analyzing the population data. The various types of surveys
include the Great Lakes Colonial Waterbird Survey, Atlantic Coast Colonial Waterbird
Survey, winter roost surveys, Christmas Bird Counts, and Breeding Bird Surveys.
Additionally, the APHIS/WS National Wildlife Research Center is involved in a variety
of DCCO research projects, including controlled experiments to assess DCCO impacts to
gross catfish production; a two-year satellite telemetry study in Alabama, Arkansas,
Louisiana, and Mississippi aimed at monitoring migratory movements of DCCOs
captured at aquaculture areas; a two-year satellite telemetry study in eastern Lake Ontario
(in cooperation with the New York State Department of Environmental Conservation)
aimed at assessing the efficacy of control activities at the Little Galloo Island breeding
colony in eastern Lake Ontario; development of a deterministic population model for
DCCOs; and preparation of a report titled “A Science-Based Initiative to Manage
Double-Crested Cormorant Damage to Southern Aquaculture.”
Information and Education Outreach. The Service participates in outreach activities to
respond to public concerns and to educate the public about DCCOs. In 1998, the
Service’s Division of Migratory Bird Management developed a fact sheet on DCCOs,
and placed it on its website at http:// migratorybirds.fws.gov/issues/cormorant/
cormorant.html. Subsequently, the cormorant subcommittee of the Service’s Great Lakes
Ecosystem Team, with involvement by State fish and wildlife agency personnel, has
produced a cormorant fact sheet series. Additionally, the Service provided funding and
production assistance to New York Sea Grant to produce the video “Managing
Cormorants in the Great Lakes.”
Service personnel have attended numerous public workshops pertaining to DCCOs and
their management, often participating with State fish and wildlife agency personnel. In
1997, the Service, together with APHIS/WS, organized a symposium on the biology and
11 – Chapter 1
management of DCCOs in the Midwest and published the proceedings (Tobin 2000). In
November 2000, the Service cooperated with University of Minnesota researchers in
putting together a one-day workshop on the DCCO-fisheries conflict, which brought
together biologists and managers from around the nation and the world. Service
personnel have also accepted many invitations to speak to citizens around the U.S. who
are interested in cormorants and the Service’s role in managing migratory birds.
1.4.5 The Role of Other Agencies in Cormorant Management
Because DCCOs fall under the authority of the MBTA, the Service has the primary
responsibility for establishing guidelines for the take of cormorants. Consequently,
management options available to States and other agencies are limited by our policies and
practices. However, some States have been and continue to be actively engaged in
research activities and the implementation of management activities authorized by the
Service.
Control Activities. A survey completed by Wires et al. (2001) found that 10 States (out of
37 States and provinces that responded to the survey) reported the use of DCCO control
methods. Six of the States employing control measures were in the southern U.S.; these
States were conducting control programs because of depredations at aquaculture facilities
and fish hatcheries. All of these States incorporated lethal and non-lethal control
measures. In the Northeast, New York and Vermont are employing control measures due
to habitat destruction and impacts to other colonial waterbirds in Lake Ontario and Lake
Champlain. Massachusetts has undertaken limited control measures at specific sites.
Additionally, the State of Oregon conducts annual DCCO harassment programs near the
Oregon coast.
Table 1. States Practicing DCCO Control (from Wires et al. 2001)
State Lethal measures Non-lethal measures
AL Shooting Harassment
AR Shooting Harassment, noise-making, decoys
LA Shooting Multiple harassment techniques
MA None Harassment
MS Shooting Harassment; Night roost dispersal program
NY Egg destruction, egg oiling Nest destruction
OK Shooting Hazing
TX Shooting Harassment
VA Yes1 Yes1
VT Egg oiling Harassment; nest destruction
1 Both lethal and non-lethal measures are undertaken, but details on specific measures employed were not
provided.
DCCOs also occur in Canada and Mexico. In Canada, DCCOs are not protected
federally and thus are managed at the provincial level. The Province of Québec has
conducted limited DCCO population control and Ontario is in the process of evaluating
the need for such action. As in the U.S., Canadian DCCO populations are generally
increasing. We are currently unaware of any involvement by Mexico in management of
DCCOs. The precise status of DCCO populations in Mexico is unknown but probably
12 – Chapter 1
stable (Wires et al. 2001). It was last estimated by Carter et al. (1995b) at about 6,969
breeding pairs.
13 – Chapter 2
CHAPTER 2: ALTERNATIVES
2.1 Introduction
This chapter, considered the “heart of the environmental impact statement” (40 CFR
1502.14), describes the six alternatives being evaluated for the purpose of managing
DCCOs in the contiguous United States. It also states the “proposed action” (Alternative
D), which is our preferred alternative for meeting the purpose and need stated in Chapter
1.
2.2 Rationale for Alternative Design
All alternatives considered were evaluated in relation to their ability to reduce resource
conflicts associated with DCCOs, increase management flexibility, and conserve healthy
populations of DCCOs over the long term. NEPA regulations require the analysis of a
No Action (or “status quo”) alternative. The other alternatives were developed after
evaluating comments received during the public scoping period, holding interagency
meetings and internal discussions, and reviewing the best available information. After
the DEIS public comment period, we discussed and developed changes to the proposed
action to improve its potential for efficacy in dealing with cormorant conflicts and in
ensuring the conservation of populations of DCCOs and other Federally-protected
species. Each alternative described below is analyzed in more detail in Chapter 4,
ENVIRONMENTAL CONSEQUENCES.
2.3 Proposed Action
The agency’s proposed action is the alternative that the agency believes would satisfy the
purpose and need (as stated in Chapter 1) and fulfill its mission and statutory
responsibilities, while giving consideration to economic, environmental, technical, and
other factors. The proposed action, Alternative D, would: (1) create a public resource
depredation order to authorize State fish and wildlife agencies, Tribes, and APHIS/WS in
24 States to control DCCOs on public and private lands and freshwaters to protect public
resources; (2) expand the aquaculture depredation order to allow winter roost control by
APHIS/WS in 13 States; and (3) allow take of DCCOs at public fish hatcheries under the
depredation orders. Based on our analysis, the proposed action would be more effective
than the current program; is environmentally sound, cost effective, and flexible enough to
meet different management needs around the country; and does not threaten the long-term
sustainability of DCCO populations or populations of any other natural resource.
2.4 Description of Alternatives
2.4.1 Alternative A: No Action (Continue existing DCCO damage management
policies)
Under this alternative, existing wildlife management policies and practices would
continue with no additional regulatory methods or strategies being authorized. This
alternative includes non-lethal management techniques (as described under Alternative
B) and activities carried out under depredation permits and the aquaculture depredation
order. Control techniques include the take of adults and young (by shooting), eggs (by
means of oiling or destruction), and active nests (by removal or destruction). Because of
Director’s Order No. 27, “Issuance of Permits to Kill Depredating Migratory Birds at
14 – Chapter 2
Fish Cultural Facilities,” depredation permits are not issued for the take of DCCOs at
National Fish Hatcheries. However, the aquaculture depredation order allows DCCOs to
be killed at State-operated fish hatcheries in 13 States (and at commercial freshwater
aquaculture facilities). All other conflicts are dealt with on a case-by-case basis,
requiring a Federal permit for every locality and occurrence where DCCO control actions
take place. All depredation permits would continue to be issued by the appropriate
Service Regional Office. Population surveys on breeding grounds would continue to be
conducted at regular intervals.
The issuance of depredation permits to take cormorants and other depredating migratory
birds is guided by the regulations found in 50 CFR §21.41. There it states that an
application for a depredation permit must be submitted to the appropriate Service
Regional Director and that each application must contain a description of the area where
depredations are occurring; the nature of the crops or other interests being injured; the
extent of such injury; and the particular species of migratory birds committing the injury.
The following table describes how the Service Regional Migratory Bird Permit Offices
have interpreted 50 CFR §21.41 and §21.47 for various resource categories.
15 – Chapter 2
Table 2. Service Practice for Issuance of Depredation Permits for DCCOs under
Alternative A (No Action)
Aquaculture
Private and State facilities in 13 States do not require a permit because they fall under the aquaculture
depredation order (AL, AR, FL, GA, KY, LA, MN, MS, NC, OK, SC, TN, and TX).
In States not covered by the depredation order APHIS/WS makes recommendations and USFWS issues
permits to take birds, eggs, and/or active nests.
Director’s Order No. 27 prohibits lethal control of fish-eating birds at “public” hatcheries except when an
“emergency” exists.
Natural Resource Issues on Public Lands/Waters
Permits issued by USFWS when action is considered necessary to ensure survival and/or recovery of
Federal- or State-listed threatened and endangered species.
Permits may be issued by USFWS if there exists convincing evidence that a regionally significant bird
population or rare and declining plant communities are being adversely affected by DCCOs.
Permits may be issued by USFWS to alleviate depredation at the site of fish stocking but requests for
permits are generally not issued for birds taking free-swimming fish in public waters.
Other Natural Resource and Economic Issues
Permits may be issued by USFWS if there is significant economic damage to privately-stocked fish on a
privately-owned water body that maximizes fishing opportunities for patrons, whether done for a fee or
for recreation.
Permits typically issued by USFWS for significant property damage (for example, physical structures or
vegetation) on public or private lands and waters.
Human Health and Safety
Permits issued by USFWS when evidence exists of significant human health and safety risks (for
example, airports or water quality).
2.4.2 Alternative B: Non-lethal Management (Do not allow lethal management
actions)
Under this alternative, permits allowing the lethal take of DCCOs or their eggs would not
be issued. The aquaculture depredation order would be revoked and depredation permits
would not be issued. To reduce impacts associated with DCCOs, this option would allow
only non-lethal management techniques such as harassment, habitat modification,
exclusion devices at production facilities, and changes in fish stocking practices.
Essentially, only those management techniques not currently requiring a Federal
depredation permit would be continued under this alternative. Population surveys would
be conducted at regular intervals.
16 – Chapter 2
2.4.3 Alternative C: Increased Local Damage Control (Expand current wildlife
damage management policy)
The intent of this alternative would be to expand the current DCCO depredation policy to
address a broader range of resource conflicts than under the No Action (see Table 3
below). The permit renewal period for DCCO depredation permits would change from
annual to biennial in order to help alleviate the increased permit review requirements
(this means that permittees would reapply for a permit every two years instead of each
year). The aquaculture depredation order would continue to allow DCCOs to be killed at
commercial freshwater aquaculture facilities and State-owned fish hatcheries in 13 States
and would be expanded to include winter roost control at aquacultural facilities in those
States. Director’s Order No. 27 prohibiting lethal control of DCCOs at public fish
hatcheries would be revoked. Non-lethal techniques would remain part of the
management program. Population surveys would be conducted at regular intervals.
17 – Chapter 2
Table 3. Service Policy for Issuance of Depredation Permits for DCCOs under
Alternative C
Aquaculture
Private and State facilities in 13 States do not require a permit because they fall under the aquaculture depredation
order (AL, AR, FL, GA, KY, LA, MN, MS, NC, OK, SC, TN, and TX). (Same as No Action)
In States not covered by the depredation order APHIS/WS makes recommendations for permit issuance and
USFWS may issue permit to take birds, eggs, and/or active nests. (Same as No Action)
Aquaculture depredation order expanded to include lethal control at winter roost sites in those 13 States. (Different
than No Action)
Director’s Order No. 27 prohibiting lethal take at public hatcheries revoked. (Different than No Action)
Natural Resource Issues on Public Lands/Waters
Permits issued by USFWS when action is considered necessary to ensure survival and/or recovery of Federal- or
State-listed threatened and endangered species. (Same as No Action)
Permits issued by USFWS for conflicts with fish, wildlife, plants, and other wild species when there is
documentation of significant impacts or when best professional judgment has determined that there is a high
likelihood that DCCOs are a significant detriment to the resource in question. In the latter case, a permit will be
issued when the control efforts will not threaten the viability of DCCO or other wildlife populations and the agency
requesting the permit prepares a site-specific management plan containing: (1) a definition of the conflict(s) with
DCCOs, including a statement of the management objectives for the area in question; (2) a description of the
evidence supporting the hypothesis that DCCOs are contributing to these resource conflicts; (3) a discussion of
other limiting factors affecting the resource (e.g., biological, environmental, socioeconomic); and (4) a discussion
of how control efforts are expected to alleviate resource conflicts. (Different than No Action)
Other Natural Resource and Economic Issues
Permits issued by USFWS if there is significant economic damage to privately-stocked fish on a privately-owned
water body that maximizes fishing opportunities for patrons, whether done for a fee or for recreation. (Same as No
Action)
Permits issued by USFWS for significant property damage (for example, physical structures or vegetation) on
public or private lands and waters. (Same as No Action)
Human Health and Safety
Permits issued by USFWS when evidence exists of significant human health and safety risks (for example, airports
water quality). (Same as No Action)
2.4.4 PROPOSED ACTION – Alternative D: Public Resource Depredation Order
(Establish a new depredation order to address public resource conflicts)
Alternative D creates a public resource depredation order to authorize State fish and
wildlife agencies, Federally-recognized Tribes, and APHIS/WS to take DCCOs found
committing or about to commit, and to prevent, depredations on the public resources of
fish (including hatchery stock at Federal, State, and Tribal facilities), wildlife, plants, and
their habitats. This authority applies to all lands and freshwaters (with appropriate
landowner permission) in 24 States (Alabama, Arkansas, Florida, Georgia, Illinois,
Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi,
18 – Chapter 2
Missouri, New York, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee,
Texas, Vermont, West Virginia, and Wisconsin). This alternative also revises the
aquaculture depredation order by specifying that it is applicable to commercial freshwater
facilities and State and Federal fish hatcheries, and by authorizing APHIS/WS employees
to take DCCOs at roost sites in the vicinity of aquaculture facilities during the months of
October, November, December, January, February, March, and April. Director’s Order
No. 27 prohibiting lethal control of DCCOs at public hatcheries will not be revoked at
this time, as was stated in the DEIS. Depredation permits would continue to be used to
address conflicts outside the authority of the depredation orders. Agencies acting under
the public resource depredation order will be required to comply with monitoring and
reporting requirements and persons operating under the aquaculture depredation order
must annually provide a current mortality log. Population surveys will be conducted at
regular intervals.
Table 4. Service Depredation Policy under Alternative D (PROPOSED ACTION)
Aquaculture
Private, State, and Federal facilities in 13 States do not require a permit because they fall under the
aquaculture depredation order. (Different than No Action)
In States not covered by the depredation order APHIS/WS makes recommendations for permit issuance and
USFWS may issue permit to take birds, eggs, and/or active nests. (Same as No Action)
Aquaculture depredation order expanded to include lethal control at winter roost sites in 13 States.
(Different than No Action)
Natural Resource and Economic Issues on Public Lands/Waters
In 24 States, State fish and wildlife agencies, Tribes, and APHIS/WS may take DCCOs to protect public
resources (fish, wildlife, plants, and their habitats) on private and public lands and freshwaters. In non-depredation
order States, depredation permits for public resource damages will be issued in accordance
with 50 CFR 21.41 and applicable Service policies. (Different than No Action)
Permits issued by USFWS for significant property damage (for example, to physical structures or
vegetation) on public or private lands and waters. (Same as No Action)
Human Health and Safety
Permits issued by USFWS when evidence exists of significant human health and safety risks (for example,
at airports or when water quality is compromised). (Same as No Action)
2.4.5 Alternative E: Regional Population Reduction (Develop population objectives
and implement actions aimed at reducing overall DCCO populations)
This alternative would entail the development of regional DCCO population objectives
designed to reduce damages associated with DCCOs. Population objectives would be
developed on an interdisciplinary, interagency basis and would be based on the best
available data, while giving consideration to other values. Control would be carried out
at nesting, roosting, wintering and all other sites in order to achieve those objectives as
rapidly as possible without adversely affecting other protected migratory birds or
threatened and endangered species. The aquaculture depredation order would allow
DCCOs to be killed at commercial freshwater aquaculture facilities and Federal, State,
and Tribal fish hatcheries in 13 States and would be expanded to include winter roost
control in those States. For all conflicts not addressed under the aquaculture depredation
Comment:
19 – Chapter 2
order or the special statewide cormorant permit, depredation permits would be issued
according to the policy outlined in Alternative C above. Non-lethal techniques would
remain part of the management program, but only voluntarily. Population surveys would
be conducted at regular intervals.
2.4.6 Alternative F: Regulated Hunting (Establish frameworks for a hunting season
on DCCOs)
Under this alternative, frameworks to develop seasons and bag limits for hunting DCCOs
would be established jointly by Federal and State wildlife agencies. These seasons would
coincide with those for waterfowl hunting. Additionally, the depredation policy outlined
in Alternative C, above, would address DCCO conflicts (issuance of depredation permits
and the aquaculture depredation order). Population monitoring would be conducted at
regular intervals.
2.5 Alternatives Considered but Eliminated from Detailed Study
2.5.1 No Management Alternative
This alternative would not allow for any Federal management or control of DCCOs (no
depredation permit issuance, no depredation order, no harassment or habitat modification,
etc.). To implement this alternative would be to ignore conflicts associated with
cormorants that must be addressed if we are to fulfill our duties to manage America’s
migratory birds responsibly. Since there is real biological and socioeconomic evidence
(as described in Chapter 3, AFFECTED ENVIRONMENT) justifying the need for
DCCO management, we find this alternative to be unreasonable (NEPA states that only
“reasonable” alternatives must be considered).
2.5.2 Rescindment of Migratory Bird Treaty Act Protection Alternative
This alternative would entail amending the MBTA and associated international
conventions to remove the DCCO from the List of Migratory Birds (those species
protected under the MBTA). DCCOs would still be protected under the laws of most
States. This action would require amending the Mexican treaty and could have the
undesirable result of losing protection for all species in the cormorant family
(Phalacrocoracidae). We feel that this would be a drastic action that would establish
precedent for removing other species and would undermine the authority of the MBTA.
2.6 Comparison of Alternatives
Each alternative described above would utilize a variety of non-lethal management
techniques. All of the alternatives we analyzed, except Alternative B, would allow for
limited lethal take (shooting, egg oiling or destruction, and/or nest destruction), either
through depredation orders or the issuance of depredation permits. Additionally,
Alternative F would develop hunting frameworks for DCCOs. Differences among
alternatives in the degree of lethal take are primarily related to the circumstances under
which permits are issued (to control local damages or to reach population objectives) and
which depredation order is in effect (aquaculture, expanded aquaculture, and/or public
resource).
20 – Chapter 2
Table 5. Actions by Alternative
Alternative Actions
Alternative A – No Action non-lethal management¹; aquaculture depredation order²;
depredation permits³
Alternative B – Non-lethal
management
non-lethal management1
Alternative C – Increased Local
Damage Control
non-lethal management1; expanded aquaculture depredation order2;
depredation permits3
Alternative D – PROPOSED
ACTION
non-lethal management1; expanded aquaculture depredation order2;
depredation permits3; public resource depredation order4
Alternative E – Regional
Population Reduction
non-lethal management1; expanded aquaculture depredation order2;
depredation permits3
Alternative F – Regulated Hunting non-lethal management1; aquaculture depredation order2;
depredation permits3, hunting seasons in participating States
¹ = includes all management techniques that are not considered “take” and thus do not
require a depredation permit (harassment, exclusion devices, habitat modification, etc.)
² = under the aquaculture depredation order, DCCOs may be taken by shooting with
firearms during daylight hours; those using shotguns are required to use nontoxic shot
³ = under depredation permits, shooting, egg oiling or destruction, and nest destruction
are the most common techniques utilized
4 = under the public resource depredation order, DCCOs may be taken by shooting, egg
oiling or destruction, nest destruction, cervical dislocation, and CO2 asphyxiation (all of
which are classified as humane euthanasia techniques for birds by the American
Veterinary Medical Association)
21 – Chapter 2
Table 6. Actions by Alternatives
A: No
Action
B: Non-lethal
Management
C:
Increased
Local
Damage
Control
PROPOSED
ACTION
D: Public
Resource
Depredation
Order
E:
Regional
Population
Reduction
F:
Regulated
Hunting
New regulatory
strategies no no no yes yes yes
Continued issuance of
depredation permits yes no yes yes yes yes
Continuation of
aquaculture depredation
order yes no yes yes yes yes
Expansion of
aquaculture depredation
order no no yes yes yes yes
Creation of public
resource depredation
order no no no yes no no
Allows take of nests yes yes yes yes yes yes
Allows take of eggs yes no yes yes yes yes
Allows take of adults
and young yes no yes yes yes yes
Allows harassment of
adults and young yes yes yes yes yes yes
Development of
regional population
objectives no no no maybe yes no
Management activities
occur on public lands yes yes yes yes yes yes
Management activities
occur on private lands yes yes yes yes yes yes
Requires additional
monitoring and
evaluation no no no yes yes yes
22 – Ch apter 3
CHAPTER 3: AFFECTED ENVIRONMENT
3.1 Introduction
The “affected environment” section of an EIS should “succinctly describe the
environment of the area(s) to be affected by the alternatives under consideration” (40
CFR 1502.15). Thus, this chapter contains a discussion of the biological and
socioeconomic environments relevant to the issues raised during scoping.
3.2 Biological Environment
3.2.1 Double-crested Cormorants
The Service’s goals in migratory bird management are to conserve DCCO populations at
sufficient levels to prevent them from becoming threatened or endangered and to ensure
that American citizens have continued opportunities to enjoy DCCOs.
Species Range. DCCOs are native to North America and range widely there. There are
essentially five different breeding populations, variously described by different authors
as: Alaska, Pacific Coast, Interior, Atlantic, and Southern. Recent population expansion,
however, has blurred the boundaries for the Interior, Atlantic, and Southern populations
(Hatch and Weseloh 1999, Wires et al. 2001). There is high variation in the migratory
tendencies of these different breeding populations. Birds that breed in Florida and
elsewhere in the Southeastern U.S. are essentially sedentary, those along the Pacific coast
are only slightly migratory, while Atlantic and Interior birds show the greatest seasonal
movements (Johnsgard 1993). The two primary migration routes appear to be down the
Atlantic coast and through the Mississippi-Missouri River valleys to the Gulf coast
(Palmer 1962) with increasing numbers of birds remaining in the Mississippi Delta
(Jackson and Jackson 1995). Refer to Appendix 2 for a map of the distribution of DCCO
breeding colonies in North America.
Habitat Requirements. In the breeding season, two factors are critical to DCCOs: suitable
nesting sites and nearby feeding grounds (van Eerden and Gregersen 1995, Hatch and
Weseloh 1999, Wires et al. 2001). Ponds, lakes, slow-moving rivers, lagoons, estuaries
and open coastlines are utilized. Small rocky or sandy islands are utilized when
available. Nests are built in trees, on structures, or on the ground. Nesting trees and
structures are usually standing in or near water, on islands, in swamps, or at tree-lined
lakes.
Nonbreeding habitats are diverse and include lakes, ponds, rivers, lagoons, estuaries,
coastal bays, marine islands, and open coastlines (Johnsgard 1993). Wintering DCCOs
require similar characteristics in feeding, loafing, and roosting sites as when breeding.
Where DCCOs winter on the coast, sandbars, shoals, coastal cliffs, offshore rocks,
channel markers, and pilings are used for roosting. Birds wintering along the lower
Mississippi River roost on perching sites such as trees, utility poles, or fishing piers and
in isolated cypress swamps (Reinhold and Sloan 1999, Wires et al. 2001). In all seasons
DCCOs require suitable places for nighttime roosts and daytime resting or loafing.
Roosts and resting places are often on exposed sites such as rocks or sandbars, pilings,
wrecks, high-tension wires, or trees near favored fishing locations (Wires et al. 2001).
23 – Ch apter 3
From the time DCCOs return to their breeding colonies in the spring until the adults are
brooding young, the colony site is their main “center of activity,” (i.e., they roost at the
colony overnight and their daily foraging activities emanate from there). While most
adults are attending young, however, auxiliary overnight roosts begin to develop. These
may be on nearby unoccupied islands or they may be several miles away. The origin of
the birds forming these roosts is not known for certain but they are most likely adults who
have failed in their breeding attempts and/or non-breeding birds. The net result is that a
new or additional “center of activity” is created in an area where the birds themselves do
not otherwise breed. These late season roosts often remain active until the birds have left
on migration in September or October. For example, DCCOs do not breed in the Bay of
Quinte, a 60 mile-long, Z-shaped bay in northeastern Lake Ontario. However, in June,
well before the migratory season, DCCOs begin to roost, at night, on islands in the bay
and their numbers increase there through September. Birds come from these islands on
daily foraging trips and have, in essence, established new centers of activity that are not
related to the breeding colony, nor are they (yet) comprised of migrant birds (D.V.
Weseloh, CWS, pers. comm.).
Double-crested Cormorant Demographics. The DCCO is the most abundant of five
species of cormorants occurring in the contiguous United States (the other species are
Great Cormorant, Neotropic Cormorant, Pelagic Cormorant, and Brandt’s Cormorant). A
conservative estimate of the total population of DCCOs in the U.S. and Canada is greater
than 1 million birds, including breeding and non-breeding individuals, but is probably
closer to 2 million (Tyson et al. 1999). We estimate that the current continental
population of DCCOs is approximately 2 million birds. This number was derived by
consulting the literature and discussing our estimate with waterbird biologists Linda
Wires (University of Minnesota), Dr. Francie Cuthbert (University of Minnesota), Dr.
Chip Weseloh (Canadian Wildlife Service), and John Trapp (USFWS). We used the
Tyson et al. estimate of 372,400 breeding pairs as our base number. We multiplied that
by 2 to get the number of breeding individuals (744,280). Then we multiplied that by
2.26, an estimate for the ratio of non-breeding to breeding birds (Weseloh unpubl. data)
that is well within the published estimates ranging from 1-4 nonbreeders per breeder).
This amounts to 1,682,073 and adding that to 744,280 comes to 2,426,353 birds total. In
2000, Chip Weseloh (unpubl. data) estimated the North American population for
breeding and non-breeding immature DCCOs (but not adult non-breeders) at 1.850
million. Based on this information and discussions with the individuals mentioned
above, we adjusted our estimate of 2.4 million to 2.0 million.
While the total number of DCCOs in North America increased rapidly from the 1970s
into the 1990s (Hatch 1995), estimates of Tyson et al. (1999) indicated that the overall
rate of growth in the U.S. and Canada slowed during the early 1990s. This is consistent
with declines in the growth rate of expanding Great Cormorant populations in
northwestern Europe (van Eerden and Gregersen 1995) and with the general rule that the
growth rate of wildlife populations decreases as it gets closer to carrying capacity.
24 – Ch apter 3
For the U.S. as a whole, according to Breeding Bird Survey (BBS) data (which are
indices of relative abundance), the breeding population of DCCOs increased at a
statistically significant rate of approximately 7.5 percent per year from 1975-2002 (Sauer
et al. 2003). Within this period, growth rates of regional populations varied substantially
and thus it is important to look at DCCO population growth rates from a regional
perspective as well. The table below summarizes the regional populations as described in
Tyson et al. 1999. The narratives that follow integrate the populations delineations used
by Tyson et al. 1999 and Wires et al. 2001. See Appendix 2 for the distribution of DCCO
breeding colonies in North America.
Table 7. DCCO Breeding Population Estimates (from Tyson et al. 1999)
Estimated # of nesting
pairs
Percent of continental
population
Estimated population
growth rate *
Atlantic 85,510 23% -6.5% (15.8%)
Interior 256,212 68% 6.0% (20.8%)
Southeast 13,604 4% 2.6% (76.9%)
West Coast-Alaska 17,084 5% -7.9% (-0.6%)
TOTAL > or = 372,410 2.6% (16.2%)
* number in parentheses indicates “category A” estimates (i.e., results of surveys in which nests were
systematically counted)
Atlantic
Twenty-three percent of North America’s DCCOs are found in the Atlantic population
(Tyson et al. 1999). In this region, DCCOs are strongly migratory and, on the coast,
occur with smaller numbers of Great Cormorants. From the early 1970s to the early
1990s, the Atlantic population increased from about 25,000 pairs to 96,000 pairs (Hatch
1995). While the number of DCCOs in this region declined by 6.5 percent overall in the
early to mid-1990s, some populations were still increasing during this period (Tyson et
al. 1999). Very large numbers breed in Quebec and the surrounding area (including the
St. Lawrence River and its estuary) and in Nova Scotia and Prince Edward Island. Very
large breeding concentrations also occur in New England along the coasts of Maine and
Massachusetts. With the exception of Maine (where numbers began declining between
the mid-1980s and early 1990s), rapid increases have occurred since the 1970s (Wires et
al. 2001). From 1977 to the 1990s, the number of DCCOs in the northeastern U.S.
increased from 17,100 nesting pairs to 34,200 pairs (Krohn et al. 1995). In parts of
southern New England (Connecticut, Rhode Island, coastal New York) the DCCO has
recently been documented as a breeding species and numbers are growing fairly rapidly.
First breeding records were obtained in New Jersey and Pennsylvania between the late
1970s and 1990s (Wires et al. 2001). The total estimated number of nesting pairs in this
population is $85,510 (Tyson et al. 1999).
Small numbers of DCCOs winter in some New England States but most Atlantic birds
winter along the coast from Virginia (where numbers of wintering birds are increasing)
southward, along the Gulf of Mexico, and in the lower Mississippi valley (Dolbeer 1991,
Hatch 1995, Wires et al. 2001).
25 – Ch apter 3
Interior
Nearly 70 percent of North American DCCOs are found in the Interior region (Tyson et
al. 1999). DCCOs in this region are highly migratory and are concentrated in the
northern prairies, particularly on the large, shallow lakes of Manitoba (Canada), which
has the largest number of breeding DCCOs in North America (Hatch 1995, Wires et al.
2001). A large number of Interior DCCOs nest on or around the Great Lakes as well, and
recent evidence indicates that they are beginning to establish themselves at small inland
lakes in the vicinity (Alvo et al. 2002). Since the early 1970s, numbers of Interior
DCCOs have increased rapidly.
From 1990 to 1997, the overall growth rate in the Interior region was estimated at 6
percent (Tyson et al. 1999) with the most dramatic increases occurring on Ontario,
Michigan, and Wisconsin waters (Wires et al. 2001). From 1970 to 1991, the Great
Lakes breeding population alone increased from 89 nests to over 38,000 nests, an average
annual increase of 29 percent (Weseloh et al. 1995). From 1991 to 1997, the number of
nests in the Great Lakes further increased to approximately 93,000, an average annual
increase of 22 percent. Nest counts in 2000 estimated 115,000 nests in the Great Lakes
(Weseloh et al. 2002). Average annual growth rates in the Great Lakes were lower for
the period 1990-2000 than the period 1980-1990 (Weseloh et al. 2002). The total
estimated number of nesting pairs in the Interior population (including Canada) is
$256,212 (Tyson et al. 1999).
Southern
Most DCCOs in this region are wintering migrants from the Interior and Atlantic regions
(Dolbeer 1991, Jackson and Jackson 1995). However, nesting DCCOs in this region are
on the rise with some nesting occurrences representing first record and others
recolonizations (Wires et al. 2001). Historically, sedentary breeding populations of
DCCOs occurred in Florida and other southern states north to North Carolina (Hatch
1995), while in recent years DCCOs have started breeding again in Arkansas, Georgia,
Mississippi, and Tennessee (Wires et al. 2001). Today, four percent of the North
American breeding population of DCCOs occurs in the Southeast region (Tyson et al.
1999). Currently, breeding colonies exist in Arkansas, Delaware, Florida, Georgia,
Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennesee, Texas, and
Virginia (Wires et al. 2001). The total estimated number of nesting pairs in this
population is >13,604 (Tyson et al. 1999).
Over the last few decades, numbers of wintering DCCOs have dramatically increased in
several southern States. Since the late 1970s, wintering DCCOs have increased by nearly
225 percent since the early 1990s in the Mississippi Delta. From an average of 30,000
DCCOs counted during the winters of 1989-93 (Glahn et al. 1996) to over 73,000
counted in the winter of 2001-2002 (G. Ellis, APHIS/WS, unpubl. data). Data from
Christmas Bird Counts conducted between 1959-1988 show increases ranging from 3.5-
18.7 percent in several States within this region, with the largest increases occurring in
Louisiana, Mississippi, and Texas (Wires et al. 2001). In New Mexico, Texas, and
Louisiana DCCOs overlap in range with Neotropic Cormorants.
26 – Ch apter 3
Pacific Coast-Alaska
Approximately 5-7 percent of North America=s DCCOs are found in this population,
which has approximately 27,500 nesting pairs according to Carter et al. (1995b) or
>17,084 pairs according to Tyson et al. (1999). Alaska DCCOs represent approximately
12 percent of the entire Pacific coast marine population (Carter et al. 1995b) and occur
with Red-faced Cormorants. Throughout their coastal range DCCOs exist with larger
numbers of Pelagic and Brandt=s Cormorants and at the southern extent of their range in
Mexico they occur with Neotropic Cormorants (Hatch 1995). Alaska breeding
populations (P. a. cincinatus) are thought to have declined since historical times, but
recent population trends are not known (Wires et al. 2001). Non-Alaska Pacific coast
breeding DCCOs (P. a. albociliatus) occur from British Columbia through Sinaloa,
Mexico. Historical declines throughout the range are well documented and recent
population status and trends for coastal populations, from British Columbia through
California, are reasonably complete. However, because recent data are not available for
significant portions of this subspecies range (e.g., Mexico and some interior areas) it is
not possible to summarize recent trends for the population as a whole. Carter et al.
(1995) documented recent increases in California and Oregon, and declines in British
Columbia, Washington, and Baja California. Tyson et al. (1999) did not consider
Mexican populations and calculated a decline for the entire West Coast-Alaska region. In
the past 20 years, the largest increases in the region have taken place in the Columbia
River Estuary, where East Sand Island supports the largest active colony along the coast
with 6,390 pairs in 2000 (Carter et al. 1995b, Collis et al. 2000, Wires et al. 2001).
Increases at East Sand Island coincided with declines in British Columbia, Washington,
and locations in interior Oregon and the rapid increase undoubtedly reflected some
immigration from these other areas (Carter et al. 1995).
Another area of recent explosive population increase is Salton Sea, California. Complete
surveys of interior California populations were conducted between 1997-1999 (Shuford
2002). Shuford estimated 6,825 pairs breeding at 29 active colonies and 80 percent of all
interior pairs occurred at Salton Sea. DCCOs at Salton Sea, increased from zero (1990-
1994) to 5,600 pairs in 1999, and then back to zero from 2001 through 2003 (Shuford
2002, C. Pelizza pers. comm.).
Factors associated with population increases. Factors contributing to the resurgence of
DCCO populations include reduced levels of environmental contaminants, particularly
DDT; increased food availability in breeding and wintering areas; and reduced human
persecution (Ludwig 1984, Vermeer and Rankin 1984, Price and Weseloh 1986, Fox and
Weseloh 1987, Hobson et al. 1989, Weseloh et al. 1995, Wires et al. 2001). A brief case
study of DCCOs in the Great Lakes provides an example of factors associated with
changes in DCCO population numbers:
In the early 1940s, DCCO populations in the American and Canadian Great Lakes were increasing rapidly
(Postupalsky 1978, Weseloh et al. 1995). After 1945, however, organochlorine pesticides came to be
widely used in the Great Lakes basin. The residues of such chemicals, particularly DDT, are ecologically
persistent and rapidly bioaccumulate in the aquatic food web, and this led to severe eggshell thinning in
DCCOs and other waterbirds. Cormorant eggs with thinned shells broke easily during incubation and led
to a period, in the 1950s and 1960s, of almost zero productivity due to low hatching success (Postupalsky
1978, Weseloh et al. 1983, Weseloh et al. 1995). Similar eggshell thinning and reproductive failure were
27 – Ch apter 3
also found in DCCOs in southern California in the late 1960s (Gress et al. 1973). Following restrictions on
the use of DDT in 1972, levels of organocholorine contaminants found in DCCO eggs declined in much of
the Great Lakes (Ryckman et al. 1998) and DCCO productivity increased accordingly during the late 1970s
(Scharf and Shugart 1981, Ludwig 1984, Noble and Elliot 1986, Price and Weseloh 1986, Bishop et al.
1992a and b). Organochlorine contaminant-related eggshell thinning no longer appears to be a major
limiting factor for DCCO reproduction on the Great Lakes (Ryckman et al. 1998), even though there are
still lingering effects of these chemicals in parts of this ecosystem three decades after they were banned
(Custer et al. 1999).
Changes in the food supply available to Great Lakes cormorants, on both the breeding
and wintering grounds, have also played a role in their population increase. Great Lakes
fish populations underwent major changes in the 20th century. Populations of forage fish
species increased significantly during the late 1950s through the 1980s, likely as a result
of dramatic declines in large, native predatory fish, such as lake trout and burbot, that
occurred during the 1940s and 1950s. These declines in larger predatory fish were
brought about by a combination of such factors as overfishing, sea lamprey predation,
and loss of spawning habitat (Weseloh et al. 1995) and led to population explosions of
smaller forage fish species. In particular, rainbow smelt and alewife, neither of which are
native to the upper Great Lakes, became very abundant in Lakes Michigan, Huron,
Ontario, and Erie through the 1970s and 1980s (Environment Canada 1995). Various
studies suggest that annual productivity and post-fledging survival of DCCO young are
high in years of alewife abundance (Palmer 1962; van der Veen 1973, Weseloh and
Ewins 1994). In fact, changes in prey abundance have been associated with increases in
populations of several fish-eating bird species worldwide (Environment Canada 1995).
The growth of the aquaculture industry has provided DCCOs with an abundant food
supply on their southern wintering grounds. The aquaculture industry (consisting largely
of channel catfish production) has experienced significant growth in the southern U.S.
over the last 20 years. While Great Lakes DCCOs historically migrated down to the
coastal areas of the Gulf of Mexico to winter, since the early 1970s wintering populations
of DCCOs in the lower Mississippi valley have been increasing (Reinhold and Sloan
1999, Glahn et al. 1996). The DCCO is the primary avian predator utilizing channel
catfish stocks (Wywialowski 1998, Reinhold and Sloan 1999). Glahn et al. (1999b)
analyzed monthly changes in body mass of wintering DCCOs in the delta region of
Mississippi and in areas without extensive aquaculture production and found that DCCO
utilization of catfish has likely increased winter survival and contributed to the
cormorant’s recent population resurgence.
Human persecution has also been a factor. DCCOs were not Federally protected until
1972. Weseloh et al. (1995) suggested that the cormorant’s initial rate of colonization
into the Great Lakes was suppressed by human persecution until the 1950s. Indeed,
destruction of DCCO nests, eggs, young, and adults, by fishermen and government
agencies, was a common occurrence in the Great Lakes basin from the 1940s into the
1960s (Baillie 1947, Omand 1947, Postupalsky 1978, Ludwig 1984, Craven and Lev
1987, Ludwig et al. 1989, Weseloh and Ewins 1994, Weseloh et al. 1995, Matteson et al.
1999) and in the Pacific Northwest (Gabrielson and Jewett 1940, Ferris 1940, Mathewson
1986, Bayer and Ferris 1987, Carter et al. 1995a). Similar control efforts, involving
large-scale spraying of eggs, occurred in Maine in the 1940s and 1950s (Gross 1951,
28 – Ch apter 3
Krohn et al. 1995, Hatch 1995) and in Manitoba on Lake Winnipegosis during the same
period (McLeod and Bondar 1953, Hatch 1995). In 1972, DCCOs were added to the list
of birds protected by the MBTA, which made it illegal to kill them in the U.S. without a
Federal permit.
Double-crested Cormorant Population Parameters. Compared to other common colonial
waterbirds, the population dynamics of DCCOs have not been well-studied (Wires et al.
2001, Hatch and Weseloh 1999). The similar life histories of DCCOs and Great
Cormorants (i.e., their being ecological counterparts), however, allow North American
managers to gain insight from management efforts in Europe (Glahn et al. 2000b). Due
to their large clutch size and persistent renesting efforts, DCCO breeding success is fairly
high compared to other North American cormorants and colonial waterbirds in general
(Johnsgard 1993).
Age at First Breeding
Van der Veen (1973) found that most birds bred for the first time at age 3 (i.e., entering
their fourth year). Johnsgard (1993, citing van Tets in Palmer 1962) also stated that “the
usual age of initial breeding in this species is probably three years, although successful
breeding has occurred among two-year-olds.” In the early 1990s, Weseloh and Ewins
(1994) observed first-breeding by many 2-year olds on Little Galloo Island in Lake
Ontario. Blackwell et al. (2002) estimated that at least 17 percent of 2-year old, and 98.4
percent of age-3+, Lake Ontario DCCOs breed.
Clutch Size
Average clutch sizes observed over the years include: 3.8 eggs in Utah (Mitchell 1977);
3.5 eggs in Maine (Mendall 1936); 3.11 eggs in Ontario (Peck and James 1983); 3.2 eggs
in Alberta (Vermeer 1969); 3.6 and 3.2 on the Madeleine Islands in Quebec (Pilon et al.
1983); 2.7-4.1 eggs, with a mode of 4, in British Columbia (van der Veen 1973); an
average of 3.12 eggs over four years on Little Galloo Island, Lake Ontario (Weseloh and
Ewins 1994); and 4.1-4.2 eggs at Columbia River Estuary colonies in Oregon (Roby et al.
1998, Collis et al. 2000).
Hatching Success
Van der Veen (1973) found that hatching success varied from 50-75 percent in DCCOs in
British Columbia. Drent et al. (1964) reported an average hatching success of 60.4
percent on Mandarte Island in British Columbia, while Mitchell (1977) observed a
hatching success of 54.2 percent in Utah. During two years of study on the Madeleine
Islands, Quebec, hatching success rates of 74.5 and 71.8 percent were observed by Pilon
et al. (1983). Roby et al. (1998) estimated hatching success in the Columbia River
Estuary to be 56 percent. Wires et al. (2001) reported that DCCO hatching success is
usually 50-75 percent.
Fledging Success
Van der Veen (1973) estimated fledging success at 74-95 percent (1.2-2.4 young per
nest). Drent et al. (1964) observed a 95 percent fledging success rate on Mandarte Island,
British Columbia, or an average of 2.4 young fledged per nest. In Utah, Mitchell (1977)
29 – Ch apter 3
reported a 72 percent fledging success rate. Pilon et al. (1983) reported fledging success
rates of 2.1 and 2.4 young per year in Québec. Slightly lower average rates of 1.8 young
fledged per nest (Hobson et al. 1989) and 1.9 young fledged per nest (Vermeer 1969)
were observed in Manitoba and Alberta, respectively. Average productivity for the Great
Lakes, between 1979 and 1991, ranged from 1.5 to 2.4 young per nest (Weseloh et al.
1995). Roby et al. (1998) and Collis et al. (2000) estimated that cormorants in the
Columbia River Estuary fledged an average of 1.6 and 1.2 chicks on East Sand Island and
2.1 and 1.6 chicks on channel markers in the estuary during 1997 and 1998, respectively.
Fowle et al. (1999) estimated productivity to be 2.5 young fledged per nest on Young
Island in Lake Champlain, Vermont. Wires et al. (2001) reported that fledging success
for DCCOs is typically 1.2-2.4 young per nest.
Survivorship
Average lifetime production has been estimated at 3.28 young per female (van der Veen
1973). Mean adult life expectancy was approximated at 6.1 years, with an estimated
first-year survival rate of 48 percent, second-year survival rate of 74 percent, and 3+
years survival rate of 85 percent (van der Veen 1973). Madenjian and Gabrey (1995)
estimated DCCO survival rates at: 58 percent from age 0 to age1; 75 percent from age 1
to 2 and age 2 to 3; and 80 percent for ages 3 to 4 and beyond. This is similar to survival
rates estimated in European Great Cormorants: 35-54 percent in the first year, 75 percent
in the second year, and 85 percent for year three and beyond (Veldkamp 1997,
Bregnballe et al. 1997). Blackwell et al. (2002) estimated that annual survival of Lake
Ontario DCCOs from fledging to just before age 1 was 30-35 percent and annual adult
survival was 85 percent. Mean annual productivity for Lake Ontario DCCOs was
estimated at 1.7-2.5 young per nest (Blackwell et al. 2002).
A major mortality factor throughout the species��� range is predation. Johnsgard (1993)
cited several studies indicating the following species as predators of DCCO chicks and/or
eggs: California Gulls, Ring-billed Gulls, Herring Gulls, Great black-backed Gulls,
American Crows, Fish Crows, Northwestern Crows, Common Ravens, and Bald Eagles.
The British Columbia Wildlife Branch has associated DCCO colony failures with
disturbance by Bald Eagles and predation by Northwestern Crows and Glaucous-winged
Gulls (1999 unpubl. data).
Other causes of mortality include disease (e.g., Newcastle disease which killed over
20,000 DCCOs in colonies in the Great Lakes, Minnesota, and North and South Dakota
in 1992 [Glaser et al. 1999]), illegal human persecution, and entanglement in fishing gear
(Hatch and Weseloh 1999). Cormorant populations are influenced by both density-dependent
and density-independent factors (Cairns 1992a), with age of first breeding,
occurrence of non-breeding, and clutch abandonment the demographic parameters most
likely to respond to density (Hatch and Weseloh 1999). In a population model developed
for great cormorants in Europe, Bregnballe et al. (1997) assumed three types of density
dependent mechanisms: increased exclusion of potential breeders, reduced fledgling
production, and increased food competition on wintering grounds.
30 – Ch apter 3
Cormorants, like other fish-eating birds, accumulate contaminants from the fish they eat.
DCCO populations declined dramatically in association with high levels of contaminants
during the 1960s and early 1970s. In fact, eggs of Herring Gulls, DCCOs, and Common
Terns were found to contain some of the highest levels of organochlorine compounds in
the world (Struger et al. 1985). Effects of chlorinated hydrocarbons on DCCOs have
been most studied in the Great Lakes, where breeding populations had accumulated high
contaminant burdens and showed severe impacts (Ryckman et al. 1998, Hatch and
Weseloh 1999). Avian eggs and carcasses in Wisconsin were examined and contained
detectable levels of several organochlorine contaminants (Dale and Stromborg 1993).
The effects of these contaminants on DCCOs includes eggshell thinning (Anderson and
Hickey 1972, Postupalsky 1978), elevated embryonic mortality (Gilbertson et al. 1991),
reproductive failure and population declines (Weseloh et al. 1983, 1995), increased adult
mortality (Greichus and Hannon 1973), increased embryonic abnormalities and crossed
bills (Fox et al. 1991, Yamashita et al. 1993, Ludwig et al. 1996), egg mortality (Tillitt et
al. 1992), and brain asymmetry (Henschel et al. 1997).
Over the years, the Service and the Canadian Wildlife Service have used fish-eating birds
such as cormorants to study the impacts of long-term exposure to persistent lipophilic
environmental contaminants within the Great Lakes ecosystem (Fox et al. 1991).
Contaminant levels started decreasing in the 1970s and have continued to do so up to the
present, with most associated biological parameters improving accordingly (Hatch and
Weseloh 1999) . For example, by 1995, most contaminant residues in DCCO eggs had
declined by 83-94 percent (Ryckman et al. 1998). However, contaminant levels in Great
Lakes DCCOs continue to be significantly higher than in most other parts of North
America (Somers et al. 1993, Sanderson et al. 1994), partly because of the long
hydrologic retention times and depth of the Great Lakes, which renders them particularly
sensitive to chemical inputs (De Vault et al. 1996).
Little work has been done on the effects or occurrence of metals in cormorants. Mercury
is most often reported, but no effects have been identified in the wild (Hatch and Weseloh
1999). Methyl mercury is highly toxic; animal studies have indicated that chronic
exposure to high mercury levels is associated with kidney damage, reproductive
problems, nervous system effects, and other health problems (Johnson et al. 1998). In
New Brunswick, total mercury concentrations in tissues of DCCOs were highest of nine
seabird species examined (Braune 1987). A study in the Carson River, Nevada, found
that DCCOs had the highest mercury concentrations of three species examined (Henny et
al. unpubl. data). Additionally, recent research on loons in New York State and New
England has shown that loons are exposed to high levels of methylmercury in these areas
(“Loons sound alarm on mercury contamination,” Natl. Geog. Today, May 16, 2003).
Because of their similar niche, it can be safely assumed that DCCOs also harbor high
mercury levels in certain areas. However, contaminants are not currently a significant
limiting factor of DCCO populations at the regional or continental scale.
Double-crested Cormorant Foraging Ecology. DCCOs are rarely seen out of sight of
land and are opportunistic, generalist feeders, preying mainly upon abundant fish species
that are easy to catch (usually slow-moving or schooling fish, ranging in size from 3-40
31 – Ch apter 3
cm [1.2-16 in]), although most commonly less than 15 cm (6 in). Glahn et al. (1998)
reported that availability (i.e., abundance), rather than size, is probably the most
important factor in prey selection, but given equal availability DCCOs prefer prey fish
that are greater than 7.5 cm (3 in) in length. They also suggested that prey fish
accessibility is important in DCCO prey selection. Neuman et al. (1997) attributed
variation in DCCO diet in Lakes Huron, Erie, and Ontario to movements of fish into
shallow spawning areas and to spatial heterogeneity of fish habitat.
Studies indicate that DCCOs have strong habitat preferences with respect to depth,
distance from the breeding colony, and distance from nearest shore (Stapanian and Bur
2002). The prey of Atlantic birds suggests that they feed at the bottom of the water
column, while that of Pacific and inland birds suggests that they feed in mid-water.
DCCOs usually forage in shallow, open water (less than 8m) within 5 km of shore (Hatch
and Weseloh 1999), although they will go farther. In freshwater lakes, DCCOs forage at
fairly shallow depths and likely take prey from all levels fairly uniformly (Johnsgard
1993). A study examining DCCOs in the western basin of Lake Erie found that the most
significant foraging pressure occurred in areas within a 20 km radius of nesting colonies,
within 3 km of shore, and in waters less than or equal to 10 m in depth (Stapanian et al.
2002). Neuman et al. (1997) determined that cormorant foraging distances at Little
Galloo Island (Lake Ontario) ranged from 3.7 to 20 km (with an average distance of 13
km). Custer and Bunk (1992) reported that birds from two colonies in the Wisconsin
waters of Lake Michigan foraged an average of 2-2.4 km from the colonies, with over 90
percent of flights being within 9 km of the colonies. In Texas, Campo et al. (1993) found
that the average estimated distance from the foraging area to the nearest shore ranged
from 20 to 975 meters.
DCCOs respond rapidly to high concentrations of fish and will congregate where fish are
easily caught, such as “put and take” lakes, stocking release sites, and aquaculture ponds
(Hatch and Weseloh 1999, Wires et al. 2001). The DCCO appears to be almost
completely diurnal in its feeding habits. When pursuing prey, it dives from the surface
and chases fish underwater. While bottom-feeding is usually solitary, DCCOs may form
loose foraging flocks when feeding on schooling prey. In this way, birds create a line
that moves forward as individuals at the rear fly short distances to “leapfrog” diving birds
in the front. DCCOs engaged in this behavior have been documented in Georgian Bay,
Ontario; Massachusetts; and Green Bay, Wisconsin, as have Great Cormorants in The
Netherlands (Glanville 1992, Custer and Bunck 1992, van Eerden and Voslamber 1995,
Hatch and Weseloh 1999). Observations of such behavior were also mentioned frequently
during the public scoping period. For specifics of foraging behavior at aquaculture
facilities see Appendix 3.
3.2.2 Fish
Among natural resource agencies, a survey conducted by Wires et al. (2001) indicated
that DCCO predation was perceived to be of major importance to sport and/or
commercial fish in at least three States (Arkansas, Tennessee, and Texas), and of
moderate importance in at least eight States (Alabama, Connecticut, Louisiana, Maine,
Massachusetts, New York, Rhode Island, and Virginia). The APHIS/WS MIS database
32 – Ch apter 3
reveals that, from FY 1995-2001, of the 29 States reporting losses to natural resources, 27
reported losses to wild fish species. During public scoping, letters received from the
following States indicated concern about impacts to sport fisheries: Arkansas, Georgia,
Illinois, Kansas, Kentucky, Louisiana, Maine, Michigan, Nebraska, New York, North
Dakota, Ohio, Oklahoma, Oregon, Texas, Vermont, Wisconsin, and Wyoming.
The diet of DCCOs consists largely of fish (generally slow-moving or schooling species),
with some occurrence of aquatic animals such as insects, crustaceans, reptiles, and
amphibians (Johnsgard 1993, Hatch and Weseloh 1999). Trapp et al. (1999) conducted a
review of diet studies carried out between 1923 and 1994 and found that of 75 fish
species detected as DCCO prey items, only 29 species comprised more than 10 percent of
the diet at a specific site and, of those 29, five species consistently comprised greater than
10 percent of the diet: alewife, brook stickleback, ninespine stickleback, yellow perch,
and slimy sculpin. These results confirm the popular notion that the DCCO is an
opportunistic feeder, utilizing a wide diversity of prey. A review of the diet literature by
Wires et al. (2001) indicated that, in general, sport and commercial fish species do not
contribute substantially to DCCO diet, although they and Trapp et al. (1999) both cited
exceptions to this rule.
In general, DCCO diet varies highly among locations and tends to reflect the fish species
composition for each location, making it necessary to examine diet on a site-specific
basis (Belyea et al. 1999, Wires et al. 2001). But some regional generalizations can be
made about fish consumed by DCCOs. On the Pacific coast, no single species emerged
as the most important prey item in past studies, although some species were very
important in certain regions. In the Columbia River Estuary, diet composition differed at
the two main colonies. At Rice Island, salmonids were the most important prey item with
stickleback and peamouth also being important; at East Sand Island, shad, herring, and
sardine were the most important prey items, with salmonids and starry flounder also
important (Collis et al. 2000). In other areas, fish such as shiner perch, sculpin, gunnel,
snake prickleback, sucker, and sand lance proved important components of DCCO diet
(Wires et al. 2001). Aside from Pacific salmonids, several of which are Federally-listed
as threatened or endangered, the populations of none of these fish species are a regional
or national concern.
In the Great Lakes, fish species such as alewife and gizzard shad, appear to be the most
important prey items. Stickleback, sculpin, cyprinids, and yellow perch and, at some
localities, burbot, freshwater drum, and lake/northern chub are also important prey fish
species (Wires et al. 2001). Stapanian et al. (2002) wrote that, “Diet and foraging studies
in the Great Lakes suggest that cormorants are opportunistic foragers that eat mostly
small prey fish, such as young-of-the-year and yearling gizzard shad…, emerald
shiner…, freshwater drum…, alewives…, and sticklebacks…,” most of which have little
sport or commercial value, while noting that “cormorants consume large quantities of
smallmouth bass and yellow perch in the waters near Little Galloo Island in Lake
Ontario.” Studies suggest that considerable temporal variation exists in the diet of Great
Lakes DCCOs (Johnson et al. 2002, Neuman et al. 1997); this can likely be attributed to
fish movement, much of which is related to spawning (Johnson et al. 2002).
33 – Ch apter 3
In the southeastern U.S., most of the diet consists of shad, catfish, and sunfish species
(Wires et al. 2001). In the Atlantic region, diet varies to a great extent, with no single
species emerging as most important. In coastal habitats, cod, sculpin, cunner, and gunnel
are important as well as sand lance and capelin. Where DCCOs are found inland or at
estuaries, alewife, rainbow smelt, stickleback, smallmouth bass, yellow perch,
pumpkinseed, cyprinids, and salmonids (mainly Atlantic salmon) are important prey
items (Wires et al. 2001). Of these species, Atlantic salmon are Federally-listed as
threatened, smallmouth bass and yellow perch are important sport fish, and cod, alewife,
and rainbow smelt are commercially fished. Concern about impacts of DCCO predation
on these fish has been expressed.
34 – Ch apter 3
Table 8. Geographic Range of Common DCCO Prey Species
Largemouth Bass: originally ranged in the Atlantic slope watersheds south of Maryland, the St. Lawrence River
basin, Great Lakes, and Mississippi River basin to northeastern Mexico. They have been stocked throughout the
United States.
Smallmouth Bass: originally ranged from Minnesota to Quebec, including the Great Lakes, southward to northern
Alabama, and west to eastern Kansas and Oklahoma. Because of its sporting qualities, it has been introduced to
many other states, Canadian provinces, and 41 other countries.
Channel Catfish: naturally occurred in the central and eastern United States and southern Canada. They ranged
throughout the Mississippi River drainage to northeast Mexico; to the east from the St. Lawrence River, along the
western slope of the Appalachian Mountains to central Florida. They were conspicuously absent along the
watersheds of the Atlantic seaboard. The species has been widely introduced for sport fishing throughout the
United States.
Walleye: native range is throughout most of eastern North America, including Great Lakes, but has been
introduced to Western North American streams where habitat is suitable.
Northern Pike: range is extensive, greater than any other freshwater game fish. Pike can be found throughout the
northern half of North America, including the Great Lakes.
Yellow Perch: on the Atlantic coast, range from South Carolina north to Nova Scotia. They can also be found west
through the southern Hudson Bay region to Saskatchewan, including the Great Lakes, and south to the northern
half of the Mississippi drainage.
Bluegill: original range includes most of central and eastern United States, north into southern Canada.
Alewife: native to the Atlantic Coast and entered the upper Great Lakes through the Welland Canal. Alewife
populations have become established in Great Lakes and many landlocked lakes in New York, Maine,
Connecticut, and other New England states.
Gizzard Shad: Mississippi and Atlantic drainages, including the Great Lakes.
Rainbow Smelt: essentially a marine species with chief distribution along Canadian coastal waters. Intruded into
fresh waters of northeastern U.S. and the Great Lakes.
Health of the Great Lakes: An Overview. In order to examine the cormorant population
explosion in the U.S. and Canadian Great Lakes and its impact to fisheries from an
“ecological” perspective, it helps to examine the ecosystem health of the Great Lakes.
An excellent overview of the aquatic community health of the Great Lakes is that of a
working paper presented at the State of the Lake Ecosystem Conference (Koonce 1995).
This discussion is derived largely from that source. By most standards, the Great Lakes
ecosystems are “extremely unhealthy.” The most notable justifications for this
description are the Lakes’ dramatic loss of biological diversity and the establishment of
non-indigenous populations (Koonce 1995).
The Great Lakes Fact Sheet produced by Environment Canada’s Ontario Region
(available online at http://www.on.ec.gc.ca/wildlife/factsheets/fs_cormorants-e.html)
provides a concise summary of the “rise and fall of Great Lakes fish populations”:
Great Lakes fish populations have undergone some profound changes in the last 60 years. One of these was
the dramatic decline of large predatory fish, primarily Lake Trout and, to a lesser extent, Burbot. In Lake
Ontario the most dramatic declines of these species occurred in the late 1930s and 1940s, while in Lake
Huron they occurred during the 1940s and 1950s. The decline of the predatory fish was caused by many
factors, including years of heavy fishing, the invasion of the sea lamprey, the loss of spawning areas.
Increased amounts of toxic contaminants entering the lakes may have also been a factor.
With the decline of larger predatory fish, the smaller fish species underwent an unprecedented population
explosion. The main species involved in this increase were Rainbow Smelt and Alewife, neither of which
was native to the upper Great Lakes. Rainbow Smelt were introduced to the Great Lakes in Michigan in
1912. They spread slowly through the lakes, becoming common in Lakes Michigan and Huron by the
35 – Ch apter 3
1930s and in Lakes Ontario and Erie by the late 1940s. Alewife were abundant in Lake Ontario by the
1890s but did not become common in Lakes Michigan and Huron until the demise of the Lake Trout in the
mid-late 1940s.
Thus, for a period of 30 years (1950s - 1970s) these smaller prey species increased in a manner more or less
unchecked by any predatory fish or birds higher up the food web. The smaller prey fish came under heavy
predation pressure in the 1980s, with the massive stocking of salmon and trout in most of the Great Lakes.
As a result, the population of smaller fish decreased. However, in spite of this predation, Alewife remained
abundant throughout much of the Great Lakes and were fed upon heavily by cormorants during this period.
Indeed, fish play a major role in structuring aquatic ecosystems. At least 18 fish species
of historical importance have declined significantly or disappeared from one or more of
the Great Lakes (Koonce 1995). Accompanying these changes in native biodiversity
have been a series of invasions and introductions of non-native fish species. Species that
have established substantial populations include: sea lamprey, alewife, rainbow smelt,
gizzard shad, white perch, carp, brown trout, Chinook salmon, coho salmon, pink salmon,
rainbow trout, ruffe, rudd, fourspine stickleback, and two species of goby. In total, 139
non-native aquatic organisms (including plants, invertebrates, and fish) have become
established in Great Lakes ecosystems (Koonce 1995).
These changes in the biodiversity of the Great Lakes have been, and continue to be,
caused by a number of chemical, physical, and biological stresses, the most important of
which include: (1) large-scale degradation of tributary and nearshore habitat for fish and
wildlife; (2) imbalances in aquatic communities due to population explosions of invading
species such as sea lamprey, alewife, white perch, and zebra and quagga mussels; (3)
reproductive failure of lake trout; (4) alterations of fish communities and loss of
biodiversity associated with overfishing and fish stocking practices; and (5) impacts of
persistent toxic chemicals on fish and wildlife (Koonce 1995).
Koonce (1995) also noted that “evaluation of the health of the aquatic community of the
Great Lakes is complicated,” mainly due to three important factors. First, identification
of factors responsible for particular population effects (e.g., increased mortality rates or
decreased reproductive rates) is difficult because different factors can produce similar
effects on populations. Second, since populations and communities are adaptive, with
healthy communities able to self-regulate in the presence of internal/external stresses, a
variety of “healthy” states may be functionally equivalent (in at least an ecological
sense). Third, the Great Lakes are disturbed ecosystems for which there are no
undisturbed communities to serve as benchmarks for recovery; thus, “the determination
of the wellness of an ecosystem requires a value judgment.”
3.2.3 Other Birds
In a survey conducted by Wires et al. (2001), impacts to other bird species were reported
by the States of Arkansas, Illinois, Iowa, Maine, Massachusetts, Michigan, Mississippi,
New York, Ohio, Vermont, and Wisconsin. Impacts to other colonial waterbirds,
particularly herons and egrets, were reported most often and these impacts were
associated mainly with habitat degradation and competition for nest sites. During our
EIS public comment periods, several resource agencies expressed concern about actual or
potential impacts to other birds.
36 – Ch apter 3
Over the course of their life cycle, individual DCCOs may interact with other species of
birds in a variety of ways. These interactions may involve competition for nest sites,
competition for food, and disease transmission.
37 – Ch apter 3
Table 9. Avian Associates of DCCOs (Source: Kaufman 1996 and Ehrlich et al. 1988)
American White Pelican: Habitat includes lakes, marshes, salt bays. Total population probably declined through
first half of 20th century, but has increased substantially since 1970s.
Anhinga: Habitat includes cypress swamps, rivers, and wooded ponds in the southern U.S.
Black-crowned Night-Heron: Habitat includes marshes and shores; roosts in trees. Populations probably declined
in 20th century due mostly to habitat loss; in recent years, overall population is generally stable or increasing, but
declining in the U.S. Great Lakes. See Table 10 below.
Brandt’s Cormorant: Habitat includes rocky areas along Pacific coast. Local populations fluctuate, but overall
numbers probably stable.
Caspian Tern: Habitat includes large lakes, coastal waters, beaches, bays. Overall population probably stable,
perhaps increasing.
Common Tern: Habitat includes lakes, ocean, bays, beaches. Northeastern populations probably lower than they
were historically. Some inland populations declining, including Great Lakes.
Great Black-backed Gull: Habitat mostly includes coastal waters and estuaries along the Atlantic coast. Populations
increasing and breeding range steadily expanding.
Great Blue Heron: Habitat includes marshes, swamps, shores, tideflats; very adaptable. Common and widespread,
numbers stable or increasing.
Great Cormorant: Habitat includes ocean cliffs with some found on large inland rivers in winter. North American
population (also found throughout Europe) has increased dramatically in recent decades, and breeding range has
expanded southward along Atlantic coast.
Great Egret: Habitat includes marshes, ponds, shores, mudflats. Nearly decimated by plume hunters in 19th century,
recovered in 20th century. In recent decades, breeding range has gradually expanded northward, with some
evidence that southern populations have declined.
Herring Gull: Habitat includes ocean coasts, bays, beaches, lakes, piers, farmlands, dumps. Populations increased
greatly in 20th century and breeding range expanded.
Neotropic Cormorant: Habitat includes tidal waters and lakes in the southern U.S. After declines in Texas numbers
in the 1950s and 1960s, is increasing again and may be spreading north inland.
Pelagic Cormorant: Habitat includes cliffs and other rocky areas along Pacific coast. Population probably stable,
with close to 75% occurring in Alaska.
Ring-billed Gull: Habitat includes lakes, bays, coasts, piers, dumps, plowed fields. Populations high and probably
still increasing.
Snowy Egret: Habitat includes marshes, swamps, ponds, shores. Nearly decimated by plume hunters in 19th
century, recovered in 20th century. Has expanded breeding range northward in recent decades; populations
increasing.
Western Gull: Habitat includes coastal waters, estuaries, beaches, offshore islands, city waterfronts. Common, with
overall numbers stable.
38 – Ch apter 3
Table 10. Comparisons of population estimates of Black-crowned Night-Herons in the
Great Lakes in 1976–80, 1989–91, and 1997–2000 (from Blokpoel and Tessier 1998;
Cuthbert et al. 2002; C. Weseloh unpubl. data; L. Harper unpubl. data)
Body of
Water
1976–1980 1989–1991 1997–2000
No. of
breeding
pairs
No. of
colonies
No. of
breeding
pairs
No. of
colonies
No. of
breeding
pairs
No. of
colonies
Lake
Michigan
558 11 859 10 927 11
Lake Huron 491 12 562 13 810 19
Lake St.
Clair
0 0 98 2 0 0
Lake Erie 4,220 2 1,719 5 529 3
Niagara
River
65 1 213 2 185 3
Lake Ontario 362 6 1,221 12 1,514 10
TOTAL 5,696 32 4,672 44 3,965 46
3.2.4 Vegetation
Concern about negative impacts of nesting and roosting DCCOs to vegetation has been
expressed by the public as well as natural resource professionals. In a survey conducted
by Wires et al. (2001) respondents from Alabama, Arkansas, Connecticut, Florida, Iowa,
Maine, Maryland, Michigan, New Hampshire, New York, North Carolina, Ohio,
Oklahoma, Rhode Island, Vermont, and Wisconsin reported impacts to trees, while the
States of Iowa, Maine, Maryland, Michigan, New Hampshire, Ohio, Oklahoma, Vermont,
Virginia, and Wisconsin reported impacts to herbaceous layers.
DCCOs seem to prefer nesting in trees to nesting on the ground, and trees are probably
used by older, more experienced, earlier-breeding individuals (Weseloh and Ewins 1994).
Along the Pacific coast, however, DCCOs nest primarily on the ground, either in low
vegetation or on the barren ground of offshore islands and coastal cliffs. Typically,
islands with avian breeding colonies have less vegetative cover than adjacent islands with
none and, in general, plant species diversity tends to be low in colonial waterbird nesting
colonies (Chapdelaine and Bédard 1995). The chief concerns associated with DCCO-induced
vegetation damage are displacement of other colonial waterbird species (caused
by habitat changes) and harm to plant species/communities of special management
significance. Into the latter category falls the Carolinian forest vegetation type, the
northernmost geographic extension of the eastern deciduous forest ecosystem. In
Canada, even though the Carolinian vegetation zone makes up only 1 percent of Canada's
total land area, it boasts a greater number of species of flora and fauna, many of which
are considered rare, than any other ecosystem in Canada
(http://www.carolinian.org/Cc1.htm).
3.2.5 Federally-listed Species
A concern among members of the public and wildlife professionals, including Service
and Wildlife Services personnel, is the impact of damage management methods and
activities on non-target species, particularly Threatened and Endangered species.
39 – Ch apter 3
Another concern is potential impacts to Threatened and Endangered species caused by
DCCOs themselves. For example, during the public scoping period, the Maine
Department of Inland Fisheries and Wildlife listed DCCO predation on stocked and
native Atlantic salmon as an issue of concern. Additionally, during the DEIS comment
period, the State of Washington stated their concern about impacts of DCCO predation on
wild salmonids.
Section 7 of the Endangered Species Act (ESA), as amended (16 U.S.C. 1531-1543; 87
Stat. 884), provides that, “The Secretary shall review other programs administered by
him and utilize such programs in furtherance of the purposes of this Act'' (and) shall
“ensure that any action authorized, funded or carried out ... is not likely to jeopardize the
continued existence of any endangered species or threatened species or result in the
destruction or adverse modification of (critical) habitat ...'' Consequently, we completed
an intra-Service biological evaluation and informal Section 7 consultation under the ESA
for the proposed action.
3.3 Socioeconomic Environment
Concerns about increasing DCCO populations extend beyond the biological to include
social and economic impacts as well.
3.3.1 Water Quality and Human Health
The major human health concern expressed during public scoping was contamination of
water supplies by DCCO excrement. Eight States expressed concern over possible
DCCO-related impacts to water quality in a survey conducted by Wires et al. (2001).
Those States were Alabama, Arkansas, Connecticut, Maine, Massachusetts, Michigan,
Rhode Island, and South Carolina. Additionally, residents of Henderson, New York, near
Little Galloo Island in eastern Lake Ontario (home to a very large DCCO colony),
expressed concern about DCCOs presenting a threat to their groundwater.
Waterbird excrement can contain coliform bacteria, streptococcus bacteria, Salmonella,
toxic chemicals, and nutrients, and it is known to compromise water quality, depending
on the number of birds, the amount of excrement, and the size of the water body.
Although the 1992 Section 305(b) State Water Quality Reports indicate that, overall, the
Nation's groundwater quality is good to excellent, many local areas have experienced
significant groundwater contamination. The sources and types of groundwater
contamination vary depending upon the region of the country, but those most frequently
reported by States include: leaking underground storage tanks, septic tanks, municipal
landfills, agricultural activities, and abandoned hazardous waste sites (EPA 1992).
Concerns about water quality and DCCOs exist on two levels: contaminants and
pathogens.
Contaminants. Elevated contaminant levels associated with breeding and/or roosting
concentrations of DCCOs and their potential effects on groundwater supplies are the
major concerns regarding DCCO impacts to human health. Metals and toxic organic
chemicals typically originate in industrial discharges, runoff from city streets, mining
activities, leachate from landfills, and a variety of other sources. These toxic chemicals,
40 – Ch apter 3
which are generally persistent in the environment, can cause death or reproductive failure
in fish, shellfish, and wildlife. In addition, they can accumulate in animal tissue, be
absorbed in sediments, or find their way into drinking water supplies, posing long-term
health risks to humans (EPA 1992).
The most toxic and persistent environmental contaminants include chlorinated
hydrocarbons (also known as organochlorine chemicals; e.g., PCBs, dioxin-like
compounds, and certain pesticides such as DDT). These compounds are lipophilic
(meaning they become chemically bound to fat molecules) and accumulate in individual
organisms via a process known as bioaccumulation. Then, as a result of
biomagnification, these chemicals, bound in organisms, occur at greater concentrations
with each step of the food chain. Thus, species at the top of the food chain, such as
DCCOs, harbor the greatest, and most toxic, levels of these contaminants.
Pathogens. Escherichia coli (E. coli) are fecal coliform bacteria associated with fecal
material of warm blooded animals. There are over 200 specific serological types of E.
coli and the majority are harmless (Sterritt and Lester 1988). Aquatic birds can be a
source of fecal contamination of water resources. For example, Simmons et al. (1995)
used genetic fingerprinting to link fecal contamination of small ponds on Fisherman
Island, Virginia to waterfowl. Klett et al. (1998) were able to implicate waterfowl and
gulls as the source of fecal coliform bacteria at the Kensico Watershed, a water supply for
New York City. Also, fecal coliform bacteria counts correlated with the number of
Canada Geese and gulls roosting at the reservoir (Klett et al. 1998). Additionally,
excessive numbers of resident Canada Geese can affect water quality around beaches and
in wetland